A Comparison of Python Class Objects and Init Files for Program Configuration

[metaperl]

A Comparison of Python Class Objects and Init Files for Program
Configuration
=

Terrence Brannon
[EMAIL PROTECTED]
http://www.livingcosmos.org/Members/sundevil/python/articles/a-comparison-of-python-class-objects-and-init-files-for-program-configuration/view



Abstract


Init files serve as a convenient mini-language for configuring
applications. The advantages of such a mini-language are

* non-technical people can edit them.
* program behavior can be configured without modifying the source

The author `has always been suspicious of mini-languages
`_, initially in the context of
dynamic HTML generation.

This document provides a comparison of two approaches to program
development, the use of `a popular Python mini-language
`_ and the use of
`Python class objects `_.

The Problem Space
-

I work for a company that takes data in various formats (e.g., CSV,
XML, Filemaker) and integrates them all into our database. The 30 or
so scripts that did this were written in Perl. I was told to rewrite
them and elected to use Python.

The Initial Rewrite Using Init Files


In the initial version using config files, I used a generic config
file and specialized/overwrote its values with a local one::

  gconfig = ConfigObj("../generic.ini")
  cnf = ConfigObj("local.ini")
  cnf.merge(gconfig)

I then proceeded to login to an FTP server and check for a certain
file and download it if it existed::

  host = ftputil.FTPHost(cnf['ke_ftp']['host'],
   cnf['ke_ftp']['user'],
   cnf['ke_ftp']['pass'])

  host.chdir(cnf['ke_ftp']['cwd'])
  found = ""
  for f in host.listdir(host.curdir):
 if f.endswith( cnf['ke_ftp']['filepattern'] ):
found = f
print "Downloading", found
host.download(f, f, 'b')

  if found == "":
 print "No file with pattern", cnf['ke_ftp']['filepattern'], "on
server"
 sys.exit()

Now lets see the object-oriented configuration
--

Instead of generic and specialized config files, one would initially
think of using inheritance when going for an OO approach. However,
each program can get configuration information from a number of
places. As a result, HAS-A will work better than IS-A in this case::

 class config(object):

   # best to use has-a because we need config info from all over the
place
   import data.config.ke

   ke = data.config.ke.ftp()
   ke.user = 'dmsdatasystems'
   ke.password = 'sredna?'
   ke.cwd  = 'DMS/companies'
   ke.filepattern = 'companies.csv.gz'

   import data.config.snap
   snap = data.config.snap.ftp()


   """
   import data.storage
   storage = data.storage.logic()
   print dir(storage)
   sys.exit()"""

 class proc(object):

   def __init__(self):
  self.cnf = config()

   def fetch_file(self):
  host = ftputil.FTPHost(self.cnf.ke.host, self.cnf.ke.user,
 self.cnf.ke.password)
  host.chdir(self.cnf.ke.cwd)

  self.downloaded_file = ""
  for f in host.listdir(host.curdir):
 if f.endswith( self.cnf.ke.filepattern ):
self.downloaded_file = f
print "Downloading", f
host.download(f, f, 'b')
print "Downloaded", f

  if self.downloaded_file == "":
 print "No file with pattern", self.cnf.ke.filepattern, "on",
self.cnf.ke.host
 sys.exit()




Evaluation
==

Appearance
--

Accessing object attributes, IMHO, is much cleaner looking. Compare::

  config['munger']['outfile']

with::

  config.munger.outfile


One takes less characters to type and lacks the noisy quote marks
(that's one of the things I miss from Perl hashes - the ability to
index into hashes using bare words without quotes).

Power
-

A mini-language is a moving target. They tend to grow and grow over
time, adding more and more ad hoc semantics and peculiarities. I'm on
the ConfigObj mailing list and they are currently discussing how to
handle multi-line config values. In Python, one simply needs to break
out """ and you are done. This epitomizes why I prefer the shortcut
of library over mini-language. The library has the full power of a
widely used, widely debugged language while the mini-language has a
smaller user community and less man hours of development behind it.

Learning Curve
--

Again, once you learn Python, you can use it for configuration as well
as programming. And Python is a very readable, clean and regular
language - it doesn't look very different from a configuration
language.

The merits of studying the syntax and semantics of a configuration
language can possibly outweigh the benefits.


Maintenance
---

It is harder to hire people with a good background in

Re: How to get the "longest possible" match with Python's RE module?

[Tim Peters]

[Licheng Fang]
>> Oh, please do have a look at the second link I've posted. There's a
>> table comparing the regexp engines. The engines you've tested probably
>> all use an NFA implementation.

[Bryan Olson]
> Unfortunately, the stuff about NFA's is wrong. Friedl's awful
> book

Strongly disagree:  it's an excellent book about the /pragmatics/ of
using "regular expressions" as most widely implemented.  It's not at
all about "regular expressions" in the  CompSci sense of the term,
which appears to be your complaint.

> was the first time I saw this confusion about what NFA is;
> I don't know if he originated the mess or just propagated it.

As far as I could tell at the time, he originated it.  I'm not happy
about that either.

> "Nondeterministic finite automata" is well defined in theory
> of computation. The set of languages accepted by NFA's is
> exactly the same as the set accepted by DFA's.

And which has very little to do with "regular expressions" as most
widely implemented -- gimmicks like backreferences are wholly outside
the DFA formalism.

> What Python uses is search-and-backtrack. Unfortunately such
> engines don't have much theory behind them, and it's hard to
> reason generally about what they do.

Yup X 3, and the last is precisely why Friedl's book is valuable for
people using "NFA" implementations:  Friedl does a good job of
explaining when and why you're likely to trigger atrocious runtime
performance, and gives practical general techniques for avoiding those
problems.  None of that has anything to do with CompSci regexps
either, but is vital knowledge for people hoping to make happy
non-trivial use of Python/Perl/etc regexps.
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Re: SQLwaterheadretard3 (Was: Is it just me, or is Sqlite3 goofy?)

[[EMAIL PROTECTED]]

Mike Owens wrote:
> And if you say SQLite misrepresents itself,
> then what do you say about MySQL, which until version 5 didn't have
> views or triggers? In fact, it didn't even have subselects until
> version 4. For a period of years, SQLite had more mainstream SQL
> features than MySQL. Yet you don't see people going around claiming
> that MySQL is not an SQL database -- that it's misrepresenting itself.

Just to be fair...

You do hear many people claiming exactly that, and the primary
complaint is often exactly the same one that's being levelled against
sqlite here (it's incredibly lax with types and does sometimes
mystifying conversions rather than pointing out programmer errors--and
yes that's intentionally loaded language that I don't necessarily agree
with, it's a common argument though.).  The lack of subselects was also
a major sticking point for a lot of people, as are other major missing
SQL features.

Not having used sqlite I can't comment on it in particular.

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Re: auto upgrade scripts?

[stefaan . himpe]

> Auto-upgrade from what to what?
> -Larry Bates

Interesting question.

In my case I want my program to check for (e.g.) bug-fix releases on
some location (network drive or ftp), and if available, allow to
automatically download and install them.
Kind of like the AutoUpgrade functionality in .net (*shudder*) ;)

Best regards,
Stefaan.

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Re: 4 Simple Questions About Python/IDLE

[Gabriel Genellina]

At Thursday 7/9/2006 13:44, Omar wrote:


I'm working through a tutorial,
http://swaroopch.info/text/Byte_of_Python:Control_Flow, and I sorta
can't get through the tutorial without overcoming these little
speedbumps.  This is why I'm asking these questions.


Have you read the Python tutorial which comes with the documentation?
You can read it online at 



Gabriel Genellina
Softlab SRL 







__ 
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http://www.yahoo.com.ar/respuestas 

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Re: Is it just me, or is Sqlite3 goofy?

[MonkeeSage]

[EMAIL PROTECTED] wrote:
> But it was stated in the sqlite docs that ALL SQL databases
> use static types implying that sqlite will be incompatible
> with any "heavy" database should the need arise to migrate
> upwards. The issue is not that there will be compatibilty
> problems with any data migration but that the truth is exactly
> opposite of what's claimed in Section 13.13.
>
> I'm not saying sqlite can't be used, what I'm asking for
> is that the documentation lay the facts out and I'll decide
> whether I can make this work in my application. Lying about
> it makes you sound like Microsoft.

I thought your qualm was with the pysqlite docs, not the sqlite docs
(which apparently do make it plain how the database handles typing)?

Also, as others have mentioned, there are a number of ways to ensure
type safety, as long as you know how the database works (which as I
understand was your original point -- that it should be better
documented how it works in the pysqlite docs; and I am inclined to
agree -- at least a mention with link to the sqlite docs would be
helpful). But given that type safety is not an issue if you use those
ways of ensuring it, then the move to a fuller database _will_ be
relatively easy. If you don't want to change anything in your database
creation/update code ala check constraints, you can always explicitly
validate from python, which can be done programatically (very simple
example -- you could also use regexp patterns to validate; e.g., string
fields not only must be type str, but must not match '^\d+$', &c):

rows = [
['1', 'fred', '0051', '/home/fred'],
['2', 'bob', '0054', '/home/bob'],
['3', 'bork', '>056', '/home/bork']
]
def validate(row):
  return [int(row[0]), str(row[1]), int(row[2]), str(row[3])]
for i in xrange(len(rows)):
  rows[i] = validate(rows[i]) # <- throws an exception on the third row
  # database stuff here...

Regards,
Jordan

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Re: PILGraph Upgrade or Alternative Suggestion

[Gabriel Genellina]

At Thursday 7/9/2006 22:35, Roger wrote:


Anyone have an updated version of PILGraph beyond 0.1a7 or a suggestion
for a light-weight alternative?


pychart



Gabriel Genellina
Softlab SRL 






__
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http://www.yahoo.com.ar/respuestas


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Re: SQLwaterheadretard3 (Was: Is it just me, or is Sqlite3 goofy?)

[MonkeeSage]

Oops! Sorry for the top-post!

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Re: Pyserial problem. script stops reading.

[Hendrik van Rooyen]

"Frederic Wenzel" <[EMAIL PROTECTED]> Wrote:>On 
9/9/06, Frederic Wenzel <[EMAIL PROTECTED]> wrote:>> On 
9/9/06, Hendrik van Rooyen <[EMAIL PROTECTED]> 
wrote:>> > | I wrote a script on Linux that uses pyserial to read 
status messages>> > | from a serial line using readlines(). For 
now, it just displays what>> > | it gets on stdout:>> 
> | (...)>> > | ser = serial.Serial(port=1,>> > 
|  
baudrate=1200,>> > 
|  
rtscts=1,>> > |>> > | If the script does not time out 
there, I am not sure what else it is>> > | doing. It seems to be in 
a wait state it does not get out of.>>When it stopped working 
again (unfortunately) I pressed ctrl c and got thefollowing 
outputÖ>>14:53 | 0008 | 02 |   | 5  |Rack 
Abs.|  -  | --752>14:53 | 0005 | 02 |   | 2  
|Rack Abs.|  -  | 00752>14:53 | 0008 | 02 |Traceback (most 
recent call last):>  File "serialhandler.py", line 34, in 
?>    lines = sh.readLines()>  File 
"serialhandler.py", line 29, in readLines>    return 
self.ser.readlines()>  File 
"/usr/lib/python2.3/site-packages/serial/serialutil.py", line 78, 
inreadlines>    line = 
self.readline(eol=eol)>  File 
"/usr/lib/python2.3/site-packages/serial/serialutil.py", line 60, 
inreadline>    c = self.read(1)>  File 
"/usr/lib/python2.3/site-packages/serial/serialposix.py", line 269, 
inread>    ready,_,_ = select.select([self.fd],[],[], 
self._timeout)>KeyboardInterrupt>>>Apparently this 
is the place where it gets stuck. The select.select>line does not return, 
not even for a timeout.>>FredThis seems a real PITA - it 
looks normal to me - it is as if the device hassimply stopped sending for 
some reason.  Can you:1) set the external device up to ignore flow 
control?2) check the cable for loose connections - wriggling it around while 
thetransmission is running might point at something - but be gentle - else 
you caneasily draw false conclusions, or break something that is in fact 
ok...does anybody else know how to check the value of the time out, what 
its for andwhat happens when it times out?- hth - 
Hendrik
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Re: Problems with email.Generator.Generator

[Max M]

Chris Withers wrote:
> Chris Withers wrote:
>> print msg.as_string()
>>
>> MIME-Version: 1.0
>> Content-Type: text/plain; charset; charset="utf-8"
> ^^^
> Actually, even this isn't correct as you can see above...
> 
>> charset = Charset('utf-8')
>> msg = MIMEText('','plain',None)
>> msg.set_payload(u'Some text with chars that need encoding:\xa3',charset)

> Has no-one ever successfully generated a correctly formatted email with 
> email.MIMEText where the message includes non-ascii characters?!

What is the problem with encoding the message as utf-8 before setting 
the payload? That has always worked for me.


pl = u'Some text with chars that need encoding:\xa3'.encode('utf-8')
msg.set_payload(pl ,charset)

 From the docs:

"""
The payload is either a string in the case of simple message objects or 
a list of Message objects for MIME container documents (e.g. multipart/* 
and message/rfc822)
"""

Message objects are always encoded strings. I don't remember seeing that 
it should be possible to use a unicode string as a message.

The charset passed in set_payload(pl ,charset) is the charset the the 
string *is* encoded in. Not the charset it *should* be encoded in.

-- 

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http://www.mxm.dk/
IT's Mad Science

Phone:  +45 66 11 84 94
Mobile: +45 29 93 42 96
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Re: egg and modpython

[Bruno Desthuilliers]

Paul Boddie wrote:
> Bruno Desthuilliers wrote:
>> Wensheng a écrit :
>>> I installed pysqlite2 using easy_install.
>>> and got this when using it from modpython:
>>> --
>>> Mod_python error: "PythonHandler etc.modpython"
> 
> [...]
> 
> I applaud you for studying the traceback in more depth than I can find
> the motivation for, Bruno. ;-) However, this looks like a program using
> some package installed by setuptools/easy_install needs to unpack that
> package when running.

Yes, this is explained in the doc. Pure Python eggs can run from zipped
files, but when there's a binary extension it has to be unzipped. The
OP's problem is that the PYTHON_EGG_CACHE env points to a directory not
writable for the user account. The two obvious solutions are to change
this env variable or reinstall the egg with the appropriate flag to
avoid installing it as a zipped egg.


>>> ExtractionError: Can't extract file(s) to egg cache
>>> The following error occurred while trying to extract file(s) to the
>>> Python egg cache:
>>>   [Errno 13] Permission denied: '/var/www/.python-eggs'
> 
> And this wants to happen apparently in the home directory of the Web
> server user, whose rights may be somewhat limited. Or perhaps one has
> to initialise setuptools for any particular user by running it first as
> that user:

No, it's just a matter of specifying another value for the PYTHON_EGG_CACHE.

> 
> [...]
> 
>>> Can peak developers fix this please?
>> Why should they "fix" something that's
>> 1/ documented
>> -> http://peak.telecommunity.com/DevCenter/EggFormats#zip-file-issues
> 
> "The Internal Structure of Python Eggs / STOP! This is not the first
> document you should read!"

That doesn't mean you should not read it.

> A case of "Beware of the Leopard" perhaps?

!-)

>> 2/ not a an egg specific issue
> 
> In my experience, most other package managers actually unpack their
> resources when invoked, rather than leaving the programs to attempt
> such things when running.

eggs are the Python's equivalent to Java's JAR, not a RPM-like. I said
it was not an egg-specific issue (which is not totally accurate) because
it mostly have to do with loading dynamic libs (.so, .dll etc) from
zipped files.

> Debian packages even compile the bytecode
> files to ensure that nothing tries (and fails) to write them to
> privileged locations afterwards.

So does eggs. But once again, eggs are *not* a general-purpose package
management system like apt, RPM, emerge etc...

(snip)
> This situation looks either a lot like a use case whose popularity has
> been underestimated by the developers - intriguing given the number of
> people supposedly using setuptools for their Web application
> deployments - or a packaging mistake with the pysqlite2 .egg file.

My VHO is that eggs needing to extract some of their content should not
be packaged as zip-safe.


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p in '[EMAIL PROTECTED]'.split('@')])"
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Re: best way of testing a program exists before using it?

[Nick Craig-Wood]

Tim Golden <[EMAIL PROTECTED]> wrote:
>  if os.path.isfile (filepath):
>print filepath

You might get a more accurate result using

  os.access(filepath, os.X_OK)

instead of

  os.path.isfile(filepath)

Which checks the file is executable

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Re: How to get the "longest possible" match with Python's RE module?

[gatti]

kondal wrote:

> This is the way the regexp works python doesn't has anything to do with
> it. It starts parsing the data with the pattern given. It returns the
> matched string acording the pattern and doesn't go back to find the
> other combinations.

I've recently had the same problem in Java, using automatically
generated regular expressions to find the longest match; I failed on
cases like matching the whole of "Abcdefg", but also the whole of
"AbCdefg" or "ABcdefg", with ([A-Z][a-z])?([A-Z][A-Za-z]{1,10})? .
No systematic way to deal with these corner cases was available, and
unsystematic ways (with greedy and reluctant quantifiers) were too
complex.
I ended up eliminating regular expressions completely and building a
dynamic programming parser that returns the set of all match lengths;
it wasn't hard and it should be even easier in Python.

Lorenzo Gatti

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Re: SQLwaterheadretard3 (Was: Is it just me, or is Sqlite3 goofy?)

[Bruno Desthuilliers]

Marty wrote:
> On 9/11/06, Mike Owens <[EMAIL PROTECTED]> wrote:
>> I coworker pointed me to this thread.
> 
> Joy for us.
> 
>>
>> < snipped good information >
> 
> In all seriousness, the information you present here is great, and
> much appreciated. Your sarcastic, condescending tone kind of gets in
> the way of the message, though.

What about jokes on "waterheadretard" then ?

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p in '[EMAIL PROTECTED]'.split('@')])"
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RE: best way of testing a program exists before using it?

[Tim Golden]

[Nick Craig-Wood]

| Tim Golden <[EMAIL PROTECTED]> wrote:
| >  if os.path.isfile (filepath):
| >print filepath
| 
| You might get a more accurate result using
| 
|   os.access(filepath, os.X_OK)
| 
| instead of
| 
|   os.path.isfile(filepath)
| 
| Which checks the file is executable

Sadly, not under Win32, hence the shenanigans with
the PATHEXT variable :)

TJG


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Re: How to get the "longest possible" match with Python's RE module?

[Licheng Fang]

Bryan Olson wrote:
> Licheng Fang wrote:
> > Oh, please do have a look at the second link I've posted. There's a
> > table comparing the regexp engines. The engines you've tested probably
> > all use an NFA implementation.
>
> Unfortunately, the stuff about NFA's is wrong. Friedl's awful
> book was the first time I saw this confusion about what NFA is;
> I don't know if he originated the mess or just propagated it.
>
> "Nondeterministic finite automata" is well defined in theory
> of computation. The set of languages accepted by NFA's is
> exactly the same as the set accepted by DFA's.
>
> What Python uses is search-and-backtrack. Unfortunately such
> engines don't have much theory behind them, and it's hard to
> reason generally about what they do.
>
>
> --
> --Bryan

Thanks for the valuable information. Indeed, when I read the pages, I
was a little confused about what it meant by 'NFA'.

But I faintly felt, there might be an indirect, and not not very exact
mapping from the search-and-backtrack strategy to NFAs in the sense of
computer science, e.g. a state machine with the capability to be in
several states at one time.

Say, when reading 'oneselfsufficient', the engine goes along the NFA
first to state 1, and then faces the choice between

one self, noneselfsufficient, none
(start)--->((1))>((2))--->((3))

1) matching 'self',
2) going on to state 2 without matching anything, or
3) just give 'one' as the matching result because state 1 is already a
terminal state

In such situations it always chooses the greedy way. To match more, it
goes to the state 2, munching 'self'. And now it's left with only
'sufficient'. Here it's choices are:

1) matching nothing and going to state 3
2) just give 'oneself' as result because state 2 is also a terminal
state

Again it's greedy, going on to state 3, in hope of matching more. But
here the pattern comes to an end, represented by state 3 as a terminal
state. So the engine gives 'oneself' as result and forgets about its
previously unexplored possibilities, because it only performs backtrack
when a match cannot be found.

I think if the backtrack is carried out in an exaustive way, we may say
the engine trys every possibility on the NFA, though it's not an NFA
itself.

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Re: BaseHTTPServer weirdness

[Steve Holden]

Ron Garret wrote:
> In article <[EMAIL PROTECTED]>,
>  Kent Johnson <[EMAIL PROTECTED]> wrote:
> 
> 
>>Steve Holden wrote:
>>
>>>Ron Garret wrote:
>>>
In article <[EMAIL PROTECTED]>,
 Steve Holden <[EMAIL PROTECTED]> wrote:



>But basically, you aren't providing a CGI environment, and that's why 
>cgi.parse() isn't working.

Clearly.  So what should I be doing?  Surely I'm not the first person to 
have this problem?

I have managed to work around this for now by copying and modifying the 
code in cgi.parse, but this still feels like a Horrible Hack to me.

>>>
>>>Let me get this right. You are aware that CGIHTTPServer module exists. 
>>>But you don't want to use that. Instead you want to use your own code. 
>>>So you have ended up duplicating some of the functionality of the cgi 
>>>library. And it feels like a hack.
>>>
>>>Have I missed anything? :-)
>>
>>Hey, be nice. Wanting to write a request handler that actually handles a 
>>POST request doesn't seem so unreasonable.
>>
>>Except...when there are about a bazillion Python web frameworks to 
>>choose from, why start from BaseHTTPServer? Why not use one of the 
>>simpler frameworks like Karrigell or Snakelets or CherryPy?
> 
> 
> It may come to that.  I just thought that what I'm trying to do is so 
> basic that it ought to be part of the standard library.  I mean, what do 
> people use BaseHTTPServer for if you can't parse form input?
> 
> 
>>Here is the query-handling code from Karrigell's CustomHTTPServer.py, 
>>good at least for a second opinion:
>>
>> def do_POST(self):
>> """Begin serving a POST request. The request data must be readable
>> on a file-like object called self.rfile"""
>> ctype, pdict = 
>>cgi.parse_header(self.headers.getheader('content-type'))
>> self.body = cgi.FieldStorage(fp=self.rfile,
>> headers=self.headers, environ = {'REQUEST_METHOD':'POST'},
>> keep_blank_values = 1, strict_parsing = 1)
>> # throw away additional data [see bug #427345]
>> while select.select([self.rfile._sock], [], [], 0)[0]:
>> if not self.rfile._sock.recv(1):
>> break
>> self.handle_data()
>>
>>Here is CherryPy's version from CP 2.1:
>>
>> # Create a copy of headerMap with lowercase keys because
>> # FieldStorage doesn't work otherwise
>> lowerHeaderMap = {}
>> for key, value in request.headerMap.items():
>> lowerHeaderMap[key.lower()] = value
>>
>> # FieldStorage only recognizes POST, so fake it.
>> methenv = {'REQUEST_METHOD': "POST"}
>> try:
>> forms = _cpcgifs.FieldStorage(fp=request.rfile,
>>   headers=lowerHeaderMap,
>>   environ=methenv,
>>   keep_blank_values=1)
>>
>>where _cpcgifs.FieldStorage is cgi.FieldStorage with some extra accessors.
> 
> 
> Here's what I actually ended up doing:
> 
> def parse(r):
>   ctype = r.headers.get('content-type')
>   if not ctype: return None
>   ctype, pdict = cgi.parse_header(ctype)
>   if ctype == 'multipart/form-data':
> return cgi.parse_multipart(r.rfile, pdict)
>   elif ctype == 'application/x-www-form-urlencoded':
> clength = int(r.headers.get('Content-length'))
> if maxlen and clength > maxlen:
>   raise ValueError, 'Maximum content length exceeded'
> return cgi.parse_qs(r.rfile.read(clength), 1)
>   else:
> return None
> 
> which is copied more or less directly from cgi.py.  But it still seems 
> to me like this (or something like it) ought to be standardized in one 
> of the *HTTPServer.py modules.
> 
> But what do I know?
> 
I wouldn't necessarily say you are wrong here, It's just that the cgi 
module has sort of "just growed", so it isn't conveniently factyored for 
reusability in other contexts. Several people (including me) have taken 
a look at it with a view to possible re-engineering and backed away 
because of the difficulty of maintaining compatibility. Python 3K will 
be an ideal oppoertunity to replace it, but until then it's probably 
going to stay in the same rather messy but working state.

regards
  Steve
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Re: Problems with email.Generator.Generator

[Peter Otten]

Chris Withers wrote:

> Okay, more out of desperation than anything else, lets try this:
> 
> from email.Charset import Charset,QP
> from email.MIMEText import MIMEText
> from StringIO import StringIO
> from email import Generator,Message
> Generator.StringIO = Message.StringIO = StringIO
> charset = Charset('utf-8')
> charset.body_encoding = QP
> msg = MIMEText(u'Some text with chars that need encoding: \xa3','plain')
> msg.set_charset(charset)
> print repr(msg.as_string())
> u'MIME-Version: 1.0\nContent-Transfer-Encoding: 8bit\nContent-Type:
> text/plain; charset="utf-8"\n\nSome text with chars that need encoding:
> \xa3'
> 
> Yay! No unicode error, but also no use:
> 
>File "c:\python24\lib\smtplib.py", line 692, in sendmail
>  (code,resp) = self.data(msg)
>File "c:\python24\lib\smtplib.py", line 489, in data
>  self.send(q)
>File "c:\python24\lib\smtplib.py", line 316, in send
>  self.sock.sendall(str)
>File "", line 1, in sendall
> UnicodeEncodeError: 'ascii' codec can't encode character u'\xa3' in
> position 297: ordinal not in range(128)

Yes, it seemed to work with your original example, but of course you have to
encode unicode somehow before sending it through a wire. A severe case of
peephole debugging, sorry. I've looked into the email package source once
more, but I fear to understand the relevant parts you have to understand it
wholesale. 

As Max suggested, your safest choice is probably passing in utf-8 instead of
unicode.

Peter
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Re: Problems with email.Generator.Generator

[Chris Withers]

Max M wrote:
>  From the docs:
> 
> """
> The payload is either a string in the case of simple message objects or 
> a list of Message objects for MIME container documents (e.g. multipart/* 
> and message/rfc822)
> """

Where'd you find that? I must have missed it in my digging :-S

> Message objects are always encoded strings. I don't remember seeing that 
> it should be possible to use a unicode string as a message.

Yes, I guess I just find that surprising in today's "everything should 
be unicode" world.

> The charset passed in set_payload(pl ,charset) is the charset the the 
> string *is* encoded in. Not the charset it *should* be encoded in.

Indeed, although there's still the bug that while set_payload can accept 
a Charset instance for its _charset parameter, the __init__ method for 
MIMENonMultipart cannot.

Incidentally, here's the class I finally ended up with:

from email.Charset import Charset
from email.MIMEText import MIMEText as OriginalMIMEText
from email.MIMENonMultipart import MIMENonMultipart

class MTText(OriginalMIMEText):

 def __init__(self, _text, _subtype='plain', _charset='us-ascii'):
 if not isinstance(_charset,Charset):
 _charset = Charset(_charset)
 if isinstance(_text,unicode):
 _text = _text.encode(_charset.input_charset)
 MIMENonMultipart.__init__(self, 'text', _subtype,
   **{'charset': _charset.input_charset})
 self.set_payload(_text, _charset)

cheers,

Chris

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Re: How to get the "longest possible" match with Python's RE module?

[Licheng Fang]

[EMAIL PROTECTED] wrote:
> kondal wrote:
>
> > This is the way the regexp works python doesn't has anything to do with
> > it. It starts parsing the data with the pattern given. It returns the
> > matched string acording the pattern and doesn't go back to find the
> > other combinations.
>
> I've recently had the same problem in Java, using automatically
> generated regular expressions to find the longest match; I failed on
> cases like matching the whole of "Abcdefg", but also the whole of
> "AbCdefg" or "ABcdefg", with ([A-Z][a-z])?([A-Z][A-Za-z]{1,10})? .
> No systematic way to deal with these corner cases was available, and
> unsystematic ways (with greedy and reluctant quantifiers) were too
> complex.
> I ended up eliminating regular expressions completely and building a
> dynamic programming parser that returns the set of all match lengths;
> it wasn't hard and it should be even easier in Python.
>
> Lorenzo Gatti

Thanks. I think make use of the expresiveness of CFG may be better
idea.

Another question: my task is to find in a given string the substrings
that satisfies a particular pattern. That's why the first tool that
came to my mind is regular expression. Parsers, however, only give a
yes/no answer to a given string. To find all substrings with a
particular pattern I may have to try every substring, which may be an
impossible task.

How can I solve this problem?

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Re: How to get the "longest possible" match with Python's RE module?

[Paul Rubin]

"Licheng Fang" <[EMAIL PROTECTED]> writes:
> I think if the backtrack is carried out in an exaustive way, we may say
> the engine trys every possibility on the NFA, though it's not an NFA
> itself.

The backtracking engine really can recognize languages that are not
describable by classical regexps, by using backreferences, negation,
etc.  But exactly what it can do is nowhere near as well-understood as
what classical regexps can do.

I seem to remember that the fully general problem of recognizing
regexps with negation is very hard, so the backtracking matcher either
has to reject some strings it should really match, or else it has to
bog down horribly with certain kinds of patterns.
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Re: Get CPU usage of a single process in Windows

[Gerrit Muller]

Tim Golden wrote:
<...snip...>
>>This should be possible as Taskmanager tracks CPU usage for every
>>process... Anyone know how this can be done?
>>
> 
> WMI can probably do the trick. If you can find something on Google
> for wmi cpu usage (or something similar) then translation to Python's
> usually quite easy. I'm fairly sure I've got an example somewhere, but
> I can't lay my hands on it at the mo.
> 
> TJG
> 
Tim Golden's general documentation/examples about WMI are at: 
.

If you have a working example of CPU usage could you post the result? I 
would be interested.

kind regards, Gerrit Muller

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Re: How to get the "longest possible" match with Python's RE module?

[gatti]

Licheng Fang wrote:

> Another question: my task is to find in a given string the substrings
> that satisfies a particular pattern. That's why the first tool that
> came to my mind is regular expression. Parsers, however, only give a
> yes/no answer to a given string. To find all substrings with a
> particular pattern I may have to try every substring, which may be an
> impossible task.

You can collect all successful parser results beginning from each index
in the string; this gives you all matches with that first index.
You could extend to multiple results general bottom-up context-free
language parsing like Earley or Tomita's algorithms; for reasonable
languages most locations can be excluded for most rules at the
beginning, with great performance improvements over trying over and
over again.

Lorenzo Gatti

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Re: Is it just me, or is Sqlite3 goofy?

[Paul Rubin]

"Mike Owens" <[EMAIL PROTECTED]> writes:
> No it doesn't. If you don't like SQLite's design decisions, write your
> own embedded relational database, and stop yapping about something you
> didn't lift a finger to create, but are clearly trying to benefit
> from.

That's silly.  The sqlite developers are making all kinds of claims on
their web site, in order to attract users and build mindshare and gain
the benefits thereof.  If the claims aren't valid, it's completely
appropriate for others to call attention to it, whether or not they
feel like doing anything to fix it.

It's just like anything else.  If you think your Congressperson is
misleading the public about something or pursuing a bad policy, you
should speak out about it.  That doesn't mean you need to run for
Congress yourself.
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Re: How to get the "longest possible" match with Python's RE module?

[Fredrik Lundh]

Licheng Fang wrote:

The idea is like this:
> 
> (*INT) = \d+
> (*DECIMAL) = (*INT)\.(*INT)
> (*FACTION) = (*DECIMAL)/(*DECIMAL)
> (*NUMERALS) = (*FACTION)|(*DECIMAL)|(*INT)
> ... ...
> 
> What's inside the sytactically wrong (* and ) is something to be
> replaced, and then I wrote a little script to do the string
> substitution

what's hiding under those ellipses?  things like "TERM" and "FACTOR" and 
"EXPRESSION", perhaps?



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deprecated python 2.5

[bussiere maillist]

DeprecationWarning: struct integer overflow masking is deprecated
  return struct.pack('>H', ~value)
 i didn't understand if someone have some explanation
and what uses instead.
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Re: [ANN] markup.py 1.5 - a lightweight HTML/XML generator

[Gerhard Häring]

Daniel Nogradi wrote:
> A new release of markup.py is available at
> 
> http://markup.sourceforge.net/
> 
> The markup module is an intuitive, lightweight, easy-to-use,
> customizable and pythonic HTML/XML generator. [...]

It's more than only a bit confusing that there's also

Markup: A toolkit for stream-based generation of markup for the web at 
http://markup.edgewall.org/ - basically a replacement for the Kid XHTML 
templating solution.

At first I was confusing your project with the other package, which I 
was planning to give a try sooner or later.

-- Gerhard

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Re: deprecated python 2.5

[John Machin]

bussiere maillist wrote:
> DeprecationWarning: struct integer overflow masking is deprecated
>   return struct.pack('>H', ~value)
>  i didn't understand if someone have some explanation
> and what uses instead.

Which 2.5 are you using? Mine (2.5c1, win32) gives me *TWO* messages,
the second of which hints at the obvious remedy:

| DOS prompt>\python25\python
| Python 2.5c1 (r25c1:51305, Aug 17 2006, 10:41:11) [MSC v.1310 32 bit
(Intel)] on
|  win32
| Type "help", "copyright", "credits" or "license" for more
information.
| >>> import struct
| >>> struct.pack('>H', 1)
| '\x00\x01'
| >>> struct.pack('>H', ~1)
| __main__:1: DeprecationWarning: struct integer overflow masking is
deprecated
| __main__:1: DeprecationWarning: 'H' format requires 0 <= number <=
65535
| '\xff\xfe'
| >>> ^Z
|
| DOS prompt>\python25\python
| Python 2.5c1 (r25c1:51305, Aug 17 2006, 10:41:11) [MSC v.1310 32 bit
(Intel)] on
|  win32
| Type "help", "copyright", "credits" or "license" for more
information.
| >>> import struct
| >>> struct.pack('>H', (~1) & 0x)
| '\xff\xfe'
| >>>

HTH,
John

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Re: deprecated python 2.5

[Fredrik Lundh]

bussiere maillist wrote:

> DeprecationWarning: struct integer overflow masking is deprecated
>   return struct.pack('>H', ~value)
>  i didn't understand if someone have some explanation
> and what uses instead.

the value doesn't fit in 16 bits.  try masking off the extra bits on the 
way in:

 struct.pack("

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RE: Get CPU usage of a single process in Windows

[Tim Golden]

[Gerrit Muller]
| 
| Tim Golden wrote:

| > WMI can probably do the trick. I'm fairly sure I've got an example 
| somewhere, but  I can't lay my hands on it at the mo.

| If you have a working example of CPU usage could you post the 
| result? I 
| would be interested.

I haven't time to revisit it just at the moment, but here's
an earlier thread in which I posted a version:

http://mail.python.org/pipermail/python-win32/2006-April/004536.html

(If it's not readable because of formatting, drop me a private
email and I'll send you a copy)
TJG


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Re: egg and modpython

[Paul Boddie]

Bruno Desthuilliers wrote:
>
> eggs are the Python's equivalent to Java's JAR, not a RPM-like. I said
> it was not an egg-specific issue (which is not totally accurate) because
> it mostly have to do with loading dynamic libs (.so, .dll etc) from
> zipped files.

True. It is notable that various Java application servers (to consider
the questioner's original problem) do unpack .war files, which probably
share more properties with .egg files than .jar files do. Indeed, I
don't recall a single occasion where I've ever needed to unpack .jar
files to have them successfully used by Java programs.

> > Debian packages even compile the bytecode
> > files to ensure that nothing tries (and fails) to write them to
> > privileged locations afterwards.
>
> So does eggs. But once again, eggs are *not* a general-purpose package
> management system like apt, RPM, emerge etc...

However, it seems to me that the setuptools and EasyInstall ecosystem,
whilst a remarkable achievement, has grown in scope sufficiently to
confuse such comparisons. Some .egg files are more than just being like
.jar files, as I note above, and with additional dependency information
included (as seems to be encouraged), one is suddenly required to deal
with a system that resembles a Python-centric package and dependency
management system rolled into one, operating in parallel with whatever
native package manager and whatever dependency management system
(they're typically separate things) that may be in operation.

Paul

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Re: Is it just me, or is Sqlite3 goofy?

[Fredrik Lundh]

Mike Owens wrote:

> Crackpot? And now we get to why I took the flamebait -- wonderfully
> constructive comments such as this.
> 
> I know SQLite's author. Besides being a nice and clearly very
> intelligent person, he also holds a master's degree in electrical
> engineering from Georgia Tech and a PhD in computer science from Duke
> University. His "crackpot" software is used by Sun, Apple, Symbian,
> Google, AOL, Philips, DLink, and I don't know how many other
> companies, not to mention countless open source projects such as
> Mozilla, PHP, and now Python.

but is he a member of Mensa?



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Re: Is it just me, or is Sqlite3 goofy?

[Fredrik Lundh]

Steve Holden wrote:

> Sure. But if you go back to the start of the thread you'll remember the 
> OP was originally complaining that SQLite was being promoted in the 
> Python docs as SQL compliant. It clearly isn't if its response to the 
> insertion of a data value that conflicts with the declared column type 
> is to store a value whose type is something else.

the standard actually says "If the value of any input parameter provided 
by the SQL-agent falls outside the set of allowed values of the data 
type of the parameter /.../ the effect is implementation-defined" so 
that's perfectly SQL92 compliant.

in fact, the phrases "is implementation-defined" and "is implementation-
dependent" occurs hundreds of times in the SQL92 standard.

it's far from obvious to me that SQL92 would rule out storing everything 
as strings ("The physical representation of a value is implementation-
dependent.") and leaving it to the language binding to map things back 
to the host language types in whatever way it wants ("Each host language 
has its own data types, which are separate and distinct from SQL data 
types", the above quotation, and so on).

looks like the real problem here is that some people think that 
"implementation-defined" means "works as it did in that other database 
I'm using", and not "specified by the implementor for each particular 
SQL-implementation".  that's not how standards work; if something's 
explicitly left undefined, it's not something you can rely on.



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Re: Is it just me, or is Sqlite3 goofy?

[Steve Holden]

Paul Rubin wrote:
> "Mike Owens" <[EMAIL PROTECTED]> writes:
> 
>>No it doesn't. If you don't like SQLite's design decisions, write your
>>own embedded relational database, and stop yapping about something you
>>didn't lift a finger to create, but are clearly trying to benefit
>>from.
> 
> 
> That's silly.  The sqlite developers are making all kinds of claims on
> their web site, in order to attract users and build mindshare and gain
> the benefits thereof.  If the claims aren't valid, it's completely
> appropriate for others to call attention to it, whether or not they
> feel like doing anything to fix it.
> 
> It's just like anything else.  If you think your Congressperson is
> misleading the public about something or pursuing a bad policy, you
> should speak out about it.  That doesn't mean you need to run for
> Congress yourself.

Though it might improve the country's politics if wanting to be a 
Congressperson was an absolute disqualification from the job.

regards
  Steve
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Re: Problems with email.Generator.Generator

[Max M]

Chris Withers wrote:
> Max M wrote:
>>  From the docs:
>>
>> """
>> The payload is either a string in the case of simple message objects 
>> or a list of Message objects for MIME container documents (e.g. 
>> multipart/* and message/rfc822)
>> """
> 
> Where'd you find that? I must have missed it in my digging :-S


End of third paragraph:

http://docs.python.org/lib/module-email.Message.html


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IT's Mad Science

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Mobile: +45 29 93 42 96
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Re: deprecated python 2.5

[bussiere maillist]

thks
Regards
Bussiere

On 9/12/06, Fredrik Lundh <[EMAIL PROTECTED]> wrote:
> bussiere maillist wrote:
>
> > DeprecationWarning: struct integer overflow masking is deprecated
> >   return struct.pack('>H', ~value)
> >  i didn't understand if someone have some explanation
> > and what uses instead.
>
> the value doesn't fit in 16 bits.  try masking off the extra bits on the
> way in:
>
>  struct.pack("
> 
>
> --
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>
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"filtered view" upon lists?

[Wildemar Wildenburger]

Hi there :)

I don't know how else to call what I'm currently implementing: An object 
that behaves like a list but doesn't store it's own items but rather 
pulls them from a larger list (if they match a certain criterion).
Changes to the filter are instantly reflected in the underlying list.
Clear enough?

Ok, so I figured that this is generic enough to be found in some 
standard module already (I've had this often enough: Painfully 
implementing s/th and then finding it in the libs some weeks later.).

Any pointers?

c.u.
wildemar
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FW: Re: [Spambayes] How to create a valid RPM?

[Edgar Matzinger]

ls,

On 09/12/2006 11:48:10 AM, [EMAIL PROTECTED] wrote:
> 
>> when I download python-spambayes-1.0rc2-2.src.rpm, install it and
>> run rpmbuild -ba ../SPECS/python-spambayes.spec, I get a lot of
>> error messages. It complains about a lot of installed but
>> unpackaged files.  How can I create a valid RPM?
> 
> Dunno.  Did you try "python setup.py bdist_rpm"?  This is a bit more

This gives the same errors. In fact it calls rpmbuild...

> general than just SpamBayes.  You might get some useful help from
> comp.lang.python (aka python-list@python.org).

   can anyone of you guys help me? It seems that the spec-file does not
contain a valid %files section.

Thanks, cu l8r, Edgar.
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Clarify Regex in Python.

[[EMAIL PROTECTED]]

After may frustrated attempts I came to know that  "match" function in
python re package actually start the matchs at the begining of the
subject, where "search" will find the given pattern any where in the
subject.

My Problem is, I want to know how can I force match functions to match
the pattern any location in the subject. i.e I want to turn off before
said behaviour.


Thanks In advance.

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Re: Running python from a usb drive

[cjl]

Jason:

Thanks! That worked...in fact, almost everything is now working as
expected (so far).

Here is my batch file:

echo "Making changes to path and file associations..."
path =
%PATH%;%CD%Python24;%CD%Python24\libs;%CD%Python24\Scripts;%CD%Python24\Lib\site-packages;%CD%Python24\DLLs
set PYTHONPATH=%CD%Python24
ASSOC .py=Python.File
ASSOC .pyc=Python.CompiledFile
ASSOC .pyo=Python.CompiledFile
ASSOC .pyw=Python.NoConFile
FTYPE Python.File=%CD%Python24\python.exe "%%1" %%*
FTYPE Python.CompiledFile=%CD%Python24\python.exe "%%1" %%*
FTYPE Python.NoConFile=%CD%Python24\pythonw.exe "%%1" %%*
set PATHTEXT=.py;%PATHTEXT%
CMD

I'm still having a problem with setting PATHTEXT...I should be able to
now type django-admin at the cmd prompt and have it work, but I need to
still type django-admin.py  ... I'm not sure what's wrong with my
setting of pathtext.

Any ideas?

Thanks again,
CJL

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RE: Get CPU usage of a single process in Windows

[Tim Golden]

[Gerrit Muller]

| If you have a working example of CPU usage could you post the 
| result? I would be interested.

OK. Here's a workingish example, cut down from the link
I posted earlier. This one was designed to work with Win2K
which I was using at the time. For WinXP and later, there's
a new counter with the ungainly name of 

Win32_PerfFormattedData_PerfProc_Process

which should give you the number straight off without having
to do the take-and-diff-and-divide dance. However, it doesn't
seem to do anything useful on my (XP) system. Haven't tried
that hard, I admit.

As ever, if you can find any example around the Web -- and there
are loads -- converting it to Python should be a breeze.

TJG


import time
import wmi

c = wmi.WMI ()

process_info = {}
while True:
  for process in c.Win32_Process ():
id = process.ProcessID
for p in c.Win32_PerfRawData_PerfProc_Process (IDProcess=id):
  n1, d1 = long (p.PercentProcessorTime), long
(p.Timestamp_Sys100NS)
  n0, d0 = process_info.get (id, (0, 0))

  try:
percent_processor_time = (float (n1 - n0) / float (d1 - d0)) *
100.0
  except ZeroDivisionError:
percent_processor_time = 0.0
  process_info[id] = (n1, d1)
  
  if percent_processor_time > 0.01:
print "%20s - %2.3f" % (process.Caption, percent_processor_time)

  print
  time.sleep (5)




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RE: Running python from a usb drive

[Tim Golden]

[cjl]

[... snip ...]

| set PATHTEXT=.py;%PATHTEXT%

| I'm still having a problem with setting PATHTEXT...

That would be because it's PATHEXT not PATHTEXT (it's sort
of like a PATH but for EXTensions).

TJG


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Re: Clarify Regex in Python.

[A.M. Kuchling]

On 12 Sep 2006 05:07:03 -0700, 
[EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
> My Problem is, I want to know how can I force match functions to match
> the pattern any location in the subject. i.e I want to turn off before
> said behaviour.

Use search() instead; that's why the method is there.

(Or put .* at the beginning of all your patterns, though that will be
slightly slower.)

--amk
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Re: Clarify Regex in Python.

[Steve Holden]

[EMAIL PROTECTED] wrote:
> After may frustrated attempts I came to know that  "match" function in
> python re package actually start the matchs at the begining of the
> subject, where "search" will find the given pattern any where in the
> subject.
> 
> My Problem is, I want to know how can I force match functions to match
> the pattern any location in the subject. i.e I want to turn off before
> said behaviour.
> 
> 
> Thanks In advance.
> 
Erm, is there some specific reason why you can't just use the search 
method? Why does it *have* to be match()?

regards
  Steve
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variable update

[km]

Hi all
Is there any handy untility for checking if  a variable is populated at runtime ? 
regards,
KM
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Help me use my Dual Core CPU!

[Simon Wittber]

I've just bought a new notebook, which has a dual core CPU.

I write cross platform games in Python, and I'd really like to be able
to use this second core (on my machine, and on user's machines) for any
new games I might write.

I know threads won't help (in CPython at least) so I'm investigating
other types of concurrency which I might be able to use. I really like
the PyLinda approach, however I need to be able to pass around all the
simple python types, which PyLinda won't help me with. Also, PyLinda is
more focused on distributing computing; I really only want to have 2
processes cooperating (or 4, if I had 4 CPUs/cores etc).

Is there any cross platform way to share python objects across
processes? (I've found POSH, but it's old, and doesn't appear to be
maintained). I could implement my own object space using shared memory,
but from what I can see, this is not available on Win32.

Are there any other concurrency options I've not discovered yet?


-Sw.

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Re: best way of testing a program exists before using it?

[Hari Sekhon]

Tim Williams wrote:
> Alternatively there is os.path.exists which works for files or
> directories, but calling it every time you use the wrapper is probably
> more expensive than using the try statement when the program *does*
> exist.
>
> import os.path
> if not os.path.exists('/dir1/dir2/filename'):
>print_something_and_exit(filename)
>
> :)
>
problem with that is that the path may change between installations on 
different machine and I can't guarantee /dir1/dir2 which is why a test 
of all dirs in the path is more portable.

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Re: Running python from a usb drive

[cjl]

Tim:

> That would be because it's PATHEXT not PATHTEXT (it's sort
> of like a PATH but for EXTensions).

Doh.

Me fail English? That's unpossible.

Thanks, I think everything is working with my poor man's movable
python.
Last on my todo list is to restore the assoc and ftype settings when
I'm done, and I found:

http://portableapps.com/node/121

Which seems to show how to do that.

CJL

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Re: markup.py 1.5 - a lightweight HTML/XML generator

[Daniel Nogradi]

> > A new release of markup.py is available at
> >
> > http://markup.sourceforge.net/
> >
> > The markup module is an intuitive, lightweight, easy-to-use,
> > customizable and pythonic HTML/XML generator. [...]
>
> It's more than only a bit confusing that there's also
>
> Markup: A toolkit for stream-based generation of markup for the web at
> http://markup.edgewall.org/ - basically a replacement for the Kid XHTML
> templating solution.
>
> At first I was confusing your project with the other package, which I
> was planning to give a try sooner or later.

Apparently markup.edgewall.org is redirected now to
genshi.edgewall.org and the name of that project became Genshi
recently, maybe exactly to avoid the confusion. Well, then this
problem has been taken care of :)

Thanks for the info anyway I quite frankly didn't know about this
other project. Perhaps I should add a note to the webpage clarifying
this.

Daniel
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Re: Clarify Regex in Python.

[[EMAIL PROTECTED]]

> Erm, is there some specific reason why you can't just use the search
> method? Why does it *have* to be match()?
>
> regards
>   Steve


I know there r many more methods to do the job, I just wonder can we
turnoff the default behaviour of match method.

Thanks.

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error

[prashant.burghate]

Hi,

Today is my first day of working on python. I want to execute python
script through C++ program. I found one very good article with example
at http://docs.python.org/ext/pure-embedding.html.
I followed the procedure as given, the code is compiled but while
running it is giving error like:
ImportError: No module named multiply
Failed to load "multiply"

Here are the steps I followed, please suggest where I am wrong and how
can I remove the above error.

Step 1: Copied the given C program into a file called test.cpp (using vi
editor)
Step 2: Compiled it using : g++ test.cpp  /usr/lib/libpython2.4.so
(created a.out)
Step 3: Wrote the given script of multipication in a file named as
multiply (using vi editor)
Step 4: But while running the program using :./a.out multiply
multiply 3 2
  Getting this error:   ImportError: No
module named multiply
  Failed to
load "multiply"

Please help me out.

Thanks & Regards,
Prashant Burghate
Project Engineer,
Embedded Systems,
Wipro Technologies, Pune.
Tel: +91-20-22933700 Extn: 51570
Mob. # 9850428252
Email: [EMAIL PROTECTED]


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Re: Get CPU usage of a single process in Windows

[Gerrit Muller]

[Tim Golden]


now I only have to find some time to play around...

thanks, Gerrit

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Re: Clarify Regex in Python.

[John Machin]

[EMAIL PROTECTED] wrote:
> > Erm, is there some specific reason why you can't just use the search
> > method? Why does it *have* to be match()?
> >
> > regards
> >   Steve
>
>
> I know there r many more methods to do the job, I just wonder can we
> turnoff the default behaviour of match method.
>

Don't wonder. Read the documentation. There is a whole section devoted
to match versus search.  If you believe there are undocumented keyword
arguments to the match method and we are wantonly withholding the
information, then you should check out your theory by downloading the
source code and reading that.

HTH,
John

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Re: Running python from a usb drive

[John Machin]

cjl wrote:
> Tim:
>
> > That would be because it's PATHEXT not PATHTEXT (it's sort
> > of like a PATH but for EXTensions).
>
> Doh.
>
> Me fail English? That's unpossible.
>
> Thanks, I think everything is working with my poor man's movable
> python.
> Last on my todo list is to restore the assoc and ftype settings when
> I'm done, and I found:
>
> http://portableapps.com/node/121
>
> Which seems to show how to do that.
>


Congratulations. Now: how much time have you spent, and how much per
hour are you worth? 

hours * dollars_per_hour < GBP_to_USD(4.99) ???

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Re: "filtered view" upon lists?

[Jorge Godoy]

Wildemar Wildenburger <[EMAIL PROTECTED]> writes:

> I don't know how else to call what I'm currently implementing: An object that
> behaves like a list but doesn't store it's own items but rather pulls them
> from a larger list (if they match a certain criterion).
> Changes to the filter are instantly reflected in the underlying list.
> Clear enough?

It looks like you're implementing a callable to me.  This is a method that
returns results based on some input -- here your original list and filter.

Then you'll use this method wherever you need that filtered list.

> Ok, so I figured that this is generic enough to be found in some standard
> module already (I've had this often enough: Painfully implementing s/th and
> then finding it in the libs some weeks later.).

I don't believe it is generic.  Nobody knows your data specs or filtering
needs. 

> Any pointers?

Use of list comprehension might make it easier to code this:


def myCallable(my_list, filter):
filtered_list = [(item) for item in my_list if filter(item)]
return filtered_list


Example of full code:

>>> test_list = range(10)
>>> filter = lambda x: not x%2
>>> def myCallable(list, filter):
... filtered_list = [(item) for item in list if filter(item)]
... return filtered_list
... 
>>> myCallable(test_list, filter)
[0, 2, 4, 6, 8]
>>> for item in myCallable(test_list, filter):
... print "See?  I'm", item
... 
See?  I'm 0
See?  I'm 2
See?  I'm 4
See?  I'm 6
See?  I'm 8
>>> 


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Re: Clarify Regex in Python.

[Fredrik Lundh]

[EMAIL PROTECTED] wrote:

> I know there r many more methods to do the job, I just wonder can we
> turnoff the default behaviour of match method.

that's not the "default behaviour", that's how match works.  if you want 
search, use search instead.



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Re: variable update

[Fredrik Lundh]

km wrote:

> Is there any handy untility for checking if  a variable is populated at 
> runtime ?

access it, and catch the NameError:

try:
variable
except NameError:
print "not defined"
else:
print "defined"

leaving variables undefined is usually bad style, though; if you can, 
assign some value to it, and test for that value instead:

variable = None

... lots of code that may assign to variable ...

if variable is not None:
print "not defined"



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RE: Help me use my Dual Core CPU!

[Tim Golden]

[Simon Wittber]

| I write cross platform games in Python, and I'd really like to be able
| to use this second core (on my machine, and on user's 
| machines) for any new games I might write.

| I know threads won't help (in CPython at least) so I'm investigating
| other types of concurrency which I might be able to use. I really like
| the PyLinda approach

I find it very elegant. I only wish I had some real-world use for it!

| Is there any cross platform way to share python objects across
| processes? (I've found POSH, but it's old, and doesn't appear to be
| maintained). I could implement my own object space using 
| shared memory, but from what I can see, this is not available on
Win32.

There is a bunch of Python sub-industries dedicated to
inter-process cooperation. But I don't know if that's
what you're after. Setting aside the strict shared-memory
option (for which I don't know of a cross-platform solution),
you have -- in particular order:

+ Pyro - http://pyro.sf.net
+ Corba - eg omniorb http://omniorb.sourceforge.net/
+ SPyRO - http://lsc.fie.umich.mx/~sadit/spyro/spyro.html
+ mmap - (built-in module) http://docs.python.org/lib/module-mmap.html
+ twisted - (because it can do everything), esp.
http://twistedmatrix.com/projects/core/spread
+ Spread - http://www.spread.org/
+ Roll-your-own sockets -
http://docs.python.org/lib/module-SocketServer.html

etc. etc. etc.

But I have the feeling I'm teaching my grandmother... Is that
the kind of thing you were after? Or not?

TJG


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Re: How to get the package, file, and line of a method/function invocant?

[metaperl]

Marc 'BlackJack' Rintsch wrote:
> In <[EMAIL PROTECTED]>, metaperl wrote:
>
> > # Of course I could cheat and pass it, but I don't want to:
> >
> > directories = data.storage.logic(__file__)
>
> Why do you consider a plain and simple solution cheating?

Hmm, I dont know the proper software engineering term, but just on the
basis of instinct, it seems wrong for a function to use something that
it can get on its own.

It's kind of like being at a 5-star hotel. It might be very possible
for you to bring your own pop tarts and toast them, but they go to
great lengths to have a continental buffet ready for you without you
doing anything.

Good question, airheaded answer :)

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Re: How to get the package, file, and line of a method/function invocant?

[metaperl]

Miki wrote:
> > > I am looking for something like the caller() routine in Perl:
> > >http://perldoc.perl.org/functions/caller.html
> >
> > Look at the inspect module in Python's standard library.
> Or is you're feeling lazy, have a look at the "here" function found in
> http://www.unixreview.com/documents/s=9133/ur0404e/ur0404e_listing1.htm

Thanks for the link. I would've never figured out how to use inspect on
my own.

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Re: error

[Rob Wolfe]

[EMAIL PROTECTED] wrote:
> Hi,
[...]
> Step 3: Wrote the given script of multipication in a file named as
> multiply (using vi editor)

The name of module should be multiply.py

HTH,
Rob

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I wish I could add docstrings to vars.

[Matthew Wilson]

I build a lot of elaborate dictionaries in my interpreter, and then I
forget exactly how they work.  It would be really nice to be able to add
notes to the dictionary.

Is there some way to do this now?

Matt


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Re: Help me use my Dual Core CPU!

[Paul Rubin]

"Simon Wittber" <[EMAIL PROTECTED]> writes:
> Are there any other concurrency options I've not discovered yet?

I've been wondering about the different Python MPI bindings that are
out there, and whether they might make sense for general purpose
concurrency when they were designed mostly for parallel numerical
computation.  Better MPI libraries should at least be able to
communicate by shared memory--I don't know if Pylinda does that.
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Re: Parsing String, Dictionary Lookups, Writing to Database Table

[Rich Shepard]

On Mon, 11 Sep 2006, [EMAIL PROTECTED] wrote:

> No, if you're going to insert into sqlite3, you don't want a csv string,
> you want a list of values (see example code below).

   Thank you very much. It makes solid sense and I can see the differences
and where I was not on track. I greatly appreciate the time and effort you
put into helping me.

Rich

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Re: error

[John Machin]

[EMAIL PROTECTED] wrote:
> Hi,
>
> Today is my first day of working on python. I want to execute python
> script through C++ program. I found one very good article with example
> at http://docs.python.org/ext/pure-embedding.html.
> I followed the procedure as given, the code is compiled but while
> running it is giving error like:
> ImportError: No module named multiply
> Failed to load "multiply"
>
> Here are the steps I followed, please suggest where I am wrong and how
> can I remove the above error.
>
> Step 1: Copied the given C program into a file called test.cpp (using vi
> editor)
> Step 2: Compiled it using : g++ test.cpp  /usr/lib/libpython2.4.so
> (created a.out)
> Step 3: Wrote the given script of multipication in a file named as
> multiply (using vi editor)

Try naming your source file multiply.py but continue to use the module
name (multiply) in the command line.  [Note: you could have a binary
extension module called multiply in a binary file called multiply.so]

I guess the author of that manual section didn't contemplate somebody
on their first day with Python doing some embedding :-)

HTH,
John

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Re: error

[John Machin]

Rob Wolfe wrote:
> [EMAIL PROTECTED] wrote:
> > Hi,
> [...]
> > Step 3: Wrote the given script of multipication in a file named as
> > multiply (using vi editor)
>
> The name of module should be multiply.py
>

module != source_file
module don't have no ferschlugginer dots in its name

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Re: Help me use my Dual Core CPU!

[Simon Wittber]

Tim Golden wrote:
> + Pyro - http://pyro.sf.net
> + Corba - eg omniorb http://omniorb.sourceforge.net/
> + SPyRO - http://lsc.fie.umich.mx/~sadit/spyro/spyro.html
> + mmap - (built-in module) http://docs.python.org/lib/module-mmap.html
> + twisted - (because it can do everything), esp.
> http://twistedmatrix.com/projects/core/spread
> + Spread - http://www.spread.org/
> + Roll-your-own sockets -
> http://docs.python.org/lib/module-SocketServer.html

For game programming purposes, I was hoping someone could point me to a
technique for sharing objects across Python processes, preferably
without any kind of marshal/unmarshal steps. It's a long shot, I know.
To be viable, I'll need to be able to pass messages between processes
very quickly. For example, It would be simple to paralellize some
graphics calculations over two processors with each process sharing a
common read-only scene data structure; however, a marshalling step in
this kind of process would be too costly.

I've used three of the libraries you mention, however, they are not
very usable for the task I had in mind, but are of course excellent for
other server based programming tasks.

> But I have the feeling I'm teaching my grandmother... Is that
> the kind of thing you were after? Or not?

I'm not familiar with the expression 'teaching my grandmother'. What
exactly does it mean?

-Sw.

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RE: Help me use my Dual Core CPU!

[Tim Golden]

| > But I have the feeling I'm teaching my grandmother... Is that
| > the kind of thing you were after? Or not?
| 
| I'm not familiar with the expression 'teaching my grandmother'. What
| exactly does it mean?

Teaching my grandmother to suck eggs (and probably several variants
with other relatives): to teach someone something they've known far
better and for far longer.

TJG


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Re: error

[Rob Wolfe]

John Machin wrote:
> Rob Wolfe wrote:
> > [EMAIL PROTECTED] wrote:
> > > Hi,
> > [...]
> > > Step 3: Wrote the given script of multipication in a file named as
> > > multiply (using vi editor)
> >
> > The name of module should be multiply.py
> >
>
> module != source_file
> module don't have no ferschlugginer dots in its name

Ooops... sorry.
I meant name of python source file, of course.

Regards,
Rob

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Validation of email

[Norman Khine]

Hello,
What is the best way to generate a long authentication string and email
this so that the user can reply and verify that the email address they
have provided is authentic, similar I guess to the way Bugzilla works?

Should this be server side or client?

How would one tackle an expiry limit on this - i.e. set the string a
time limit?

Any useful links of implementations in python are most welcomed.

Cheers

Norman

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Re: How to get the package, file, and line of a method/function invocant?

[metaperl]

Marc 'BlackJack' Rintsch wrote:
> In <[EMAIL PROTECTED]>, metaperl wrote:
>
> > # Of course I could cheat and pass it, but I don't want to:
> >
> > directories = data.storage.logic(__file__)
>
> Why do you consider a plain and simple solution cheating?
>

Ok now I figured it out. The reason is that this function will be used
by many "client" classes. If we use the plain and simple solution, our
codebase increases in size, because each client class will supply the
function. Not only that, but they might make an error in what they
send.

By having the "server" class do the work, the code base decreases in
size and the amount of errors drops.

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Re: SQLwaterheadretard3 (Was: Is it just me, or is Sqlite3 goofy?)

[Mike Owens]

On 12 Sep 2006 00:15:41 -0700, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:

> Just to be fair...
>
> You do hear many people claiming exactly that, and the primary
> complaint is often exactly the same one that's being levelled against
> sqlite here (it's incredibly lax with types and does sometimes
> mystifying conversions rather than pointing out programmer errors--and
> yes that's intentionally loaded language that I don't necessarily agree
> with, it's a common argument though.).

True enough.

Yet not a single conversion is undocumented in SQLite, nor is its type
affinity. It works exactly as advertised. And MySQL's chief type
conversion gotchas -- primarily dates/times I think -- were also
clearly addressed in the documentation, and where changed in later
versions of MySQL. Then there is, as I think another person pointed
out on this thread, Oracle's silent conversion of empty strings to
NULLs in VARCHAR fields -- talk about mystifying. What about Oracle's
native date format, which also has no relation to the standard? I have
little experience with Oracle, but from what I can tell, to get it to
display dates in standard (ISO) format, you have to set the
NLS_DATE_FORMAT at the session or database level, which requires
either additional SQL commands, or administrative intervention. More
so-called non-SQL compliant behavior, although hardly a surprise (or
even a problem) to someone who is experienced with Oracle.

The bottom line: to use *any* database effectively, big or small, one
has to read its documentation, not the SQL standard.
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Re: question about including something like sqlite in python

[John Salerno]

Dan Sommers wrote:

> It's difficult to imagine
> any one developer (or development shop) using the entire library, so at
> least one module must be extraneous.

That's a good point. I guess I am just trying to figure out why I'm a 
little surprised sqlite was included, but at the same time I'm excited 
to use it and the fact that it will now be standard has caused me to 
look into more than otherwise. :)
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Re: Running python from a usb drive

[cjl]

John:

> Congratulations. Now: how much time have you spent, and how much per
> hour are you worth? hours * dollars_per_hour < GBP_to_USD(4.99) ???

Since you mention it, I am currently earning about $200 an hour (when
I'm working), and I spent about 3 hours on this, so this cost me about
$600. I think 4.99 GBP (the price of movable python) translates to
about 9 or 10 dollars. So all told this cost me about $590.

Well worth it at twice the price, because I did it myself, I learned
from doing it, others my learn from it, and it is "open", unlike
movable python.

Any ideas about how to set file type associations without writing to
the registry?

Thanks again,
CJL

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RE: Running python from a usb drive

[Tim Golden]

[cjl]

| Any ideas about how to set file type associations without writing to
| the registry?

Well, yes. Just the same as was in the article you pointed
to... or have I missed something?

assoc .py=python.file
ftype python.file="c:\python24\python.exe" "%1" %*

(or whatever version of Python).

Obviously switching like this is prone to the difficulties
outlined there: if something crashes and you don't change
back, you're stuck until you change it back manually.

TJG


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Re: Secure XMLRPC Server / PEM Files

[Laszlo Nagy]

Daniel Crespo írta:
> Hi Laszlo,
>
> I have read that. It's the wrapper for the usage of OpenSSL, so I have
> to install it. I have downloaded the Borland C++ compiler, and I'm
> doing so right now, but I'm not getting good results yet.
>   
You do not need any compiler. You just need to install the openssl 
binaries and the wrapper.
> I tried to import OpenSSL, it seems to work.
>   
Great.
> Now, I want to try the code I submited earlier, but I need the .pem
> files. You told me to change generate.sh to generate.bat. How can I do
> that?
>   

Basically, use "del" instead of "rm" and use "move" instead of "mv". Use 
 instead of $1. Moreover, openssl.exe must be on your 
path. That's all.

Try this (untested):

openssl req -config openssl.cnf -new -out my-server.csr
openssl rsa -in privkey.pem -out my-server.key
openssl x509 -in my-server.csr -out my-server.cert -req -signkey my-server.key 
-days 1500
openssl x509 -in my-server.cert -out my-server.der.crt -outform DER

move my-server.csr yourdomain.com.csr
move my-server.cert yourdomain.com.cert.pem
move my-server.key yourdomain.com.key.pem
move my-server.der.crt yourdomain.com.der.crt

del privkey.pem


  Laszlo

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Re: I wish I could add docstrings to vars.

[Neil Cerutti]

On 2006-09-12, Matthew Wilson <[EMAIL PROTECTED]> wrote:
> I build a lot of elaborate dictionaries in my interpreter, and
> then I forget exactly how they work.  It would be really nice
> to be able to add notes to the dictionary.
>
> Is there some way to do this now?

Writing a thin wrapper around the dictionary might be beneficial,
and would also furnish a place for the docstrings. Actually, the
wrapper would probably prevent you from needing the docstring
very often. ;)

-- 
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Eddie Robinson is about one word: winning and losing. --Eddie
Robinson's agent Paul Collier
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Re: "filtered view" upon lists?

[Paul McGuire]

"Jorge Godoy" <[EMAIL PROTECTED]> wrote in message 
news:[EMAIL PROTECTED]
> Wildemar Wildenburger <[EMAIL PROTECTED]> writes:
>
>> I don't know how else to call what I'm currently implementing: An object 
>> that
>> behaves like a list but doesn't store it's own items but rather pulls 
>> them
>> from a larger list (if they match a certain criterion).
>> Changes to the filter are instantly reflected in the underlying list.
>> Clear enough?
>
> It looks like you're implementing a callable to me.  This is a method that
> returns results based on some input -- here your original list and filter.
>
> Then you'll use this method wherever you need that filtered list.
>
>> Ok, so I figured that this is generic enough to be found in some standard
>> module already (I've had this often enough: Painfully implementing s/th 
>> and
>> then finding it in the libs some weeks later.).
>
> I don't believe it is generic.  Nobody knows your data specs or filtering
> needs.
>
>> Any pointers?
>
> Use of list comprehension might make it easier to code this:
>
>
> def myCallable(my_list, filter):
>filtered_list = [(item) for item in my_list if filter(item)]
>return filtered_list
>
>
> Example of full code:
>
 test_list = range(10)
 filter = lambda x: not x%2
 def myCallable(list, filter):
> ... filtered_list = [(item) for item in list if filter(item)]
> ... return filtered_list
> ...
 myCallable(test_list, filter)
> [0, 2, 4, 6, 8]
 for item in myCallable(test_list, filter):
> ... print "See?  I'm", item
> ...
> See?  I'm 0
> See?  I'm 2
> See?  I'm 4
> See?  I'm 6
> See?  I'm 8

>
>
> -- 
> Jorge Godoy  <[EMAIL PROTECTED]>

Functionally-speaking, there is the filter built-in that does this same 
thing:

>>> data = range(10)
>>> odds = filter(lambda x : x % 2, data)
>>> evens = filter(lambda x : x % 2 != 1, data)
>>> odds
[1, 3, 5, 7, 9]
>>> evens
[0, 2, 4, 6, 8]


-- Paul


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Re: SQLwaterheadretard3 (Was: Is it just me, or is Sqlite3 goofy?)

[Fredrik Lundh]

Mike Owens wrote:

> The bottom line: to use *any* database effectively, big or small, one
> has to read its documentation, not the SQL standard.

note that the SQL standard tells you to read the documentation for the 
database you're using, in at least 149 places (*).



*) See Annex B.  I only have a draft edition; the number of items in the 
final version may differ.

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RE: Running python from a usb drive

[Tim Golden]

| [cjl]
| 
| | Any ideas about how to set file type associations without writing to
| | the registry?
| 
  [Tim Golden]
| Well, yes. Just the same as was in the article you pointed
| to... or have I missed something?

Ah, I see. Presumably the FTYPE / ASSOC commands write things
to the registry behind the scenes. So I assume you mean: 
without writing anything away permanently
which might then be held there in the case of a crash. Well, I
don't think so. You could, I supposed have a script which reset
any associations to their default which could then set up to run
on startup, but I don't know how viable that is for your situation.

TJG


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Re: Help me use my Dual Core CPU!

[Paul Rubin]

"Simon Wittber" <[EMAIL PROTECTED]> writes:
> For game programming purposes, I was hoping someone could point me to a
> technique for sharing objects across Python processes, preferably
> without any kind of marshal/unmarshal steps. It's a long shot, I know.
> To be viable, I'll need to be able to pass messages between processes
> very quickly. For example, It would be simple to paralellize some
> graphics calculations over two processors with each process sharing a
> common read-only scene data structure; however, a marshalling step in
> this kind of process would be too costly.

If it's for some specific calculation in the game, the bluntest
approach is probably to write a C extension that releases the GIL to
do the calculation, and then use ordinary threads for concurrency.
Put appropriate locks in the object to synchronize on.
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Re: Is it just me, or is Sqlite3 goofy?

[Mike Owens]

On 11 Sep 2006 21:35:28 -0700, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
> Mike Owens wrote:
> > On 11 Sep 2006 18:23:50 -0700, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
> >
> > > Can you run your car on diesel fuel?
> > >
> > > Why not?
> > >
> > > Because your car's specification says to use gasoline?
> > >
> > > If your car has been designed to run on diesel, you shouldn't
> > > be saying it has gasoline engine. Duh.
> >
> > No but you can still call it a car with an engine, just as SQLite is a
> > SQL database, with an SQL engine.
>
> Seperate the data from the engine and what have you got?
> Data with dynamic typing. Data that can't be migrated to
> a "real" SQL database because you'll get type mismatches
> when strings are inserted into numeric fields. The type affinity
> kluge won't help there, will it?

Did you even read my original post? Or did you just completely miss the point?

> It's not the job of the System Test Engineer to design things.
> It's his job to find fault with everything. I just happen to be very
> good at finding faults with things.

And apparently not very good at providing any constructive solutions.

> But no one appreciates my finding those faults.

No one appreciates the tone in which you report these alleged faults,
necessarily agrees with the faults that you find, nor elected you
system test engineer of the SQLite project.

> > It calls for other things that many databases don't implement or
> > altogether violate as well, so what? Show me how both MS SQL's T-SQL
> > and Oracle's PL/SQL procedure languages are so standards compliant
> > that you can use the same procedure code in both databases. You can't
> > -- precisely because they ignore or outright violate parts of the
> > standard as well. What's your position on that? Do some Googling and
> > you can easily find 18 ways that Oracle's PL/SQL deviates from the
> > standard. And T-SQL is plainly nowhere close.
>
> And how many of those systems use dynamic typing?

And how many conform to the standard?

> Name one where the documentation claims the SQL Language
> Specification is a bug.

Name one that conforms to the standard.

> And a lot of people go to chiropractors. And chiropractors are
> nice intelligent people with degrees. And the therapy provided
> does good.
>
> Nevertheless, the theory on which it's based is quackery.

To use your specious analogy, it represents another way of doing
things, which you admit yourself works. That's your justification for
calling Richard Hipp a crackpot?

> > It's clear. You're just way too smart for SQLite.
>
> Did you see my solution to Rick Shepard's problem in the
> thread "Parsing String, Dictionary Lookups, Writing to
> Database Table"?

The point being? -- you can write Python code and feel entitled to
condescending and rude?
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Re: variable update

[Steve Holden]

Fredrik Lundh wrote:
> km wrote:
> 
> 
>>Is there any handy untility for checking if  a variable is populated at 
>>runtime ?
> 
> 
> access it, and catch the NameError:
> 
> try:
> variable
> except NameError:

In a function when accessing a not-yet-bound local variable you may also 
(as Fredrik knows but didn't bother to say) see an UnboundLocalError 
exception,

> print "not defined"
> else:
> print "defined"
> 
> leaving variables undefined is usually bad style, though; if you can, 
> assign some value to it, and test for that value instead:
> 
> variable = None
> 
> ... lots of code that may assign to variable ...
> 
> if variable is not None:
> print "not defined"
> 
regards
  Steve
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Re: best way of testing a program exists before using it?

[Nick Craig-Wood]

Tim Golden <[EMAIL PROTECTED]> wrote:
>  [Nick Craig-Wood]
> 
> | Tim Golden <[EMAIL PROTECTED]> wrote:
> | >  if os.path.isfile (filepath):
> | >print filepath
> | 
> | You might get a more accurate result using
> | 
> |   os.access(filepath, os.X_OK)
> | 
> | instead of
> | 
> |   os.path.isfile(filepath)
> | 
> | Which checks the file is executable
> 
>  Sadly, not under Win32, hence the shenanigans with
>  the PATHEXT variable :)

Make a patch for os.access()?  It says in the docs it works on
Windows!

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From bags to default dicts

[Mark E. Fenner]

Hello all,

I was curious if anyone has transitioned some code from using Raymond
Hettinger's bag class:

http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/259174

to using 2.5's collections.defaultdict.  Any pitfalls to watch out for?  It
seems we should be able to do slightly better than creating a bag class
that has a defaultdict as a member.  So, inheriting from defaultdict and
defining some of the nice utility methods that Hettinger's class defines
seems like the way to go.  Comments?

Regards,
Mark
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Are Python's reserved words reserved in places they dont need to be?

[metaperl]

  -->  python -i
>>> class = "algebra"
  File "", line 1
class = "algebra"
  ^
SyntaxError: invalid syntax
>>>


Why isn' t the parser smart enough to see that class followed by an
identifier is used for class definition but class followed by equals is
a simple assignment?

Also, I had a bug where I tried to set the attributes "user" and "pass"
in an object but "pass" would not work because it is a reserved word.
Again pass should be reserved in certain contexts but not others.

Is Python 3k going to fix this sort of thing?

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RE: best way of testing a program exists before using it?

[Tim Golden]

| Tim Golden <[EMAIL PROTECTED]> wrote:
| >  [Nick Craig-Wood]
| > 
| > | Tim Golden <[EMAIL PROTECTED]> wrote:
| > | >  if os.path.isfile (filepath):
| > | >print filepath
| > | 
| > | You might get a more accurate result using
| > | 
| > |   os.access(filepath, os.X_OK)
| > | 
| > | instead of
| > | 
| > |   os.path.isfile(filepath)
| > | 
| > | Which checks the file is executable
| > 
| >  Sadly, not under Win32, hence the shenanigans with
| >  the PATHEXT variable :)

[Nick Craig-Wood]
| Make a patch for os.access()?  It says in the docs it works on
| Windows!

I suspect it might end up being a doc patch. AFAICR the os-specific 
stuff is implemented in C; I'll try downloading the source at some 
point and having a look.

The existing docs do say, though:

"""
Note: I/O operations may fail even when access() indicates that 
they would succeed, particularly for operations on network filesystems 
which may have permissions semantics beyond the usual POSIX
permission-bit model. 
"""

Don't know if this covers the case meanwhile.

TJG


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Re: Are Python's reserved words reserved in places they dont need to be?

[Diez B. Roggisch]

metaperl schrieb:
>   -->  python -i
 class = "algebra"
>   File "", line 1
> class = "algebra"
>   ^
> SyntaxError: invalid syntax
> 
> 
> Why isn' t the parser smart enough to see that class followed by an
> identifier is used for class definition but class followed by equals is
> a simple assignment?
> 
> Also, I had a bug where I tried to set the attributes "user" and "pass"
> in an object but "pass" would not work because it is a reserved word.
> Again pass should be reserved in certain contexts but not others.

Most parsers are written in a way that makes keywords reserved, 
regardless of their occurrence. That is because it is way easier to do 
so. And the few reserved words won't matter usually.

> Is Python 3k going to fix this sort of thing?

Don't think so.

Diez
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Re: Are Python's reserved words reserved in places they dont need to be?

[Richard Brodie]

"metaperl" <[EMAIL PROTECTED]> wrote in message 
news:[EMAIL PROTECTED]

> Why isn' t the parser smart enough to see that class followed by an
> identifier is used for class definition but class followed by equals is
> a simple assignment?

Because it's simpler to reserve words than worry about possible
ambiguities in all past and future use cases. If you could use it
as an identifier, it wouldn't be a reserved word by the normal
definition of the term. 


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Code to add docstrings to classes

[Matthew Wilson]

On Tue 12 Sep 2006 10:06:27 AM EDT, Neil Cerutti wrote:
> Writing a thin wrapper around the dictionary might be beneficial,
> and would also furnish a place for the docstrings. 

I wrote a function that hopefully does just that.  I'm not very savvy at
doing this class-factory stuff, so any advice would be welcome.

def vd(C):

"""

Return a subclass of class C that has a instance-level attribute _vardoc.

"""

class VDC(C):

def __init__(self, *args, **kwargs):

vardoc = kwargs.get('vardoc')
if vardoc:
assert isinstance(vardoc, str), "vardoc must be a
string!"
kwargs.pop('vardoc')
self._vardoc = vardoc

C.__init__(self, *args, **kwargs)

def __repr__(self):

if self._vardoc:
return self._vardoc + "\n" + C.__repr__(self)

else:
return C.__repr__(self)

return VDC


def test_vd():

i = vd(int)(6)
i._vardoc = "integer!"
assert isinstance(i, int)

d = vd(dict)(a=1, b=2, c=i, vardoc="dict!")
assert d['a'] == 1
assert d['c'] == 6
assert isinstance(d, dict)



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Re: question about including something like sqlite in python

[skip]

John> I guess I am just trying to figure out why I'm a little surprised
John> sqlite was included, but at the same time I'm excited to use it
John> and the fact that it will now be standard has caused me to look
John> into more than otherwise. :)

You might find some of the discussion on the python-dev mailing list
instructive:


http://www.google.com/search?hs=Phn&hl=en&lr=&client=firefox-a&rls=org.mozilla%3Aen-US%3Aofficial&q=site%3Amail.python.org%2Fpipermail%2Fpython-dev+sqlite&btnG=Search

This thread looks particularly interesting (and rather long-lived):

http://mail.python.org/pipermail/python-dev/2004-October/049534.html

Skip
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Re: best way of testing a program exists before using it?

[skip]

Nick> Tim Golden <[EMAIL PROTECTED]> wrote:
>> [Nick Craig-Wood]
>> 
>> | Tim Golden <[EMAIL PROTECTED]> wrote:
>> | >  if os.path.isfile (filepath):
>> | >print filepath
>> | 
>> | You might get a more accurate result using
>> | 
>> |   os.access(filepath, os.X_OK)
>> | 
>> | instead of
>> | 
>> |   os.path.isfile(filepath)
>> | 
>> | Which checks the file is executable

Just picking up this thread late.  Note that access() doesn't do what you
want unless your real and effective user ids are the same.  Granted, that's
the case most of the time, but not always...

Skip
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Re: Are Python's reserved words reserved in places they dont need to be?

[Istvan Albert]

metaperl wrote:
> -->  python -i
> >>> class = "algebra"
>   File "", line 1
> class = "algebra"
>   ^
> SyntaxError: invalid syntax

Designing a syntax to avoid all possible newbie errors is impractical
because as soon as you are finished with one iteration the new newbies
will start making different kinds of errors...

Take solace in the fact that you've been immediately notifed of the
error while its fix: renaming pass to passwd is trivial ...

i.

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Re: Looking for the Perfect Editor

[Omar]

thanks for all the responses...

I'm liking the way ulipad and scite work

I'd switch to ulipad entirely if I canget to recognize the python
interpreter in the preferences menu.  I can't seem to figure that out.

Also, I'm highly interested in getting the snippets manager working.

any ideas?

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RE: best way of testing a program exists before using it?

[Tim Golden]

[EMAIL PROTECTED]
| Sent: 12 September 2006 16:04
| To: python-list@python.org
| Subject: Re: best way of testing a program exists before using it?
| 
| Nick> Tim Golden <[EMAIL PROTECTED]> wrote:
| >> [Nick Craig-Wood]
| >> 
| >> | Tim Golden <[EMAIL PROTECTED]> wrote:
| >> | >  if os.path.isfile (filepath):
| >> | >print filepath
| >> | 
| >> | You might get a more accurate result using
| >> | 
| >> |   os.access(filepath, os.X_OK)
| >> | 
| >> | instead of
| >> | 
| >> |   os.path.isfile(filepath)
| >> | 
| >> | Which checks the file is executable
| 
| Just picking up this thread late.  Note that access() doesn't 
| do what you
| want unless your real and effective user ids are the same.  
| Granted, that's
| the case most of the time, but not always...

Also, I just looked at the implementation in posixmodule.c,
and at the msdn article on its use, and at a thread in python-dev
a year or so ago. The last -- where someone was proposing more
specifics if the call fails -- didn't really go anywhere, and is
full of people (GvR and others) saying: don't use os.access unless...

The msdn article: http://msdn2.microsoft.com/en-us/library/1w06ktdy.aspx
doesn't even seem to suggest that checking for executableness is a
possibility, and I think that the posixmodule.c code is simply
swallowing any non-OK return value and saying: No. (The msdn page
suggests that invalid parameters will return EINVAL).

All that said, I think the only thing would be to add a line to
the docs saying sthg like: This will always return False for X_OK under
Win32. I'm happy to submit the patch, but is it worth it?

TJG


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Re: Clarify Regex in Python.

[[EMAIL PROTECTED]]

k, people, thanks for ur replys.

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Re: variable update

[Bruno Desthuilliers]

Fredrik Lundh wrote:
(snip)
> 
>variable = None
> 
>... lots of code that may assign to variable ...
> 
>if variable is not None:
>print "not defined"

Shouldn't that be:
 if variable is None:
 print "not defined"

?-)

Note to the OP: if None is a valid value for the variable, you may use
another object, ie:

def somefunc(*args, **kw):
  variable = _marker = object()

  (...)

  if variable is _marker:
 print "not defined"

  (...)

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Re: egg and modpython

[Bruno Desthuilliers]

Paul Boddie wrote:
> Bruno Desthuilliers wrote:
>> eggs are the Python's equivalent to Java's JAR, not a RPM-like. I said
>> it was not an egg-specific issue (which is not totally accurate) because
>> it mostly have to do with loading dynamic libs (.so, .dll etc) from
>> zipped files.
> 
> True. It is notable that various Java application servers (to consider
> the questioner's original problem) do unpack .war files, which probably
> share more properties with .egg files than .jar files do. Indeed, I
> don't recall a single occasion where I've ever needed to unpack .jar
> files to have them successfully used by Java programs.

AFAIK, jar files don't include native dynamic libs... But I'm not a Java
expert (happily forgot most of what I used to know about this language).

>>> Debian packages even compile the bytecode
>>> files to ensure that nothing tries (and fails) to write them to
>>> privileged locations afterwards.
>> So does eggs. But once again, eggs are *not* a general-purpose package
>> management system like apt, RPM, emerge etc...
> 
> However, it seems to me that the setuptools and EasyInstall ecosystem,
> whilst a remarkable achievement, has grown in scope sufficiently to
> confuse such comparisons. Some .egg files are more than just being like
> .jar files, as I note above, and with additional dependency information
> included (as seems to be encouraged), one is suddenly required to deal
> with a system that resembles a Python-centric package and dependency
> management system rolled into one, operating in parallel with whatever
> native package manager and whatever dependency management system
> (they're typically separate things) that may be in operation.

Yes, true. But I'd still say that it's more a problem of proper
packaging (ie, an egg with dynamic libs inside should better not be
packaged as 'zip-safe') than a bug in the eggs system itself.

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Re: Is it just me, or is Sqlite3 goofy?

[Paul Rubin]

"Mike Owens" <[EMAIL PROTECTED]> writes:
> > It's not the job of the System Test Engineer to design things.
> > It's his job to find fault with everything. I just happen to be very
> > good at finding faults with things.
> 
> And apparently not very good at providing any constructive solutions.

As he says, it's not his job.

> > But no one appreciates my finding those faults.
> 
> No one appreciates the tone in which you report these alleged faults,

Your tone is not so great either.

> necessarily agrees with the faults that you find, nor elected you
> system test engineer of the SQLite project.

It's an open source project, as you like to say.  Everyone is a test
engineer.

> > > standard as well. What's your position on that? Do some Googling and
> > > you can easily find 18 ways that Oracle's PL/SQL deviates from the
> > > standard. And T-SQL is plainly nowhere close.
> >
> > And how many of those systems use dynamic typing?
> 
> And how many conform to the standard?

How many of those deviations are justified in their documentation by
the responsible parties claiming, in effect, that they're smarter than
the standard's designers?

It seems obvious to me that there should, at minimum, be an option to
turn this particular nonstandard behavior on and off.
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Re: "filtered view" upon lists?

[Wildemar Wildenburger]

Jorge Godoy wrote:
 > Wildemar Wildenburger <[EMAIL PROTECTED]> writes:
 >
 >> I don't know how else to call what I'm currently implementing: An 
object that
 >> behaves like a list but doesn't store it's own items but rather 
pulls them
 >> from a larger list (if they match a certain criterion).
 >> Changes to the filter are instantly reflected in the underlying list.
 >> Clear enough?
 >
 > It looks like you're implementing a callable to me.  This is a method 
that
 > returns results based on some input -- here your original list and 
filter.
 > Then you'll use this method wherever you need that filtered list.
 >
Ok, so I'm not clear enough ;) .
I don't just want to extract certain elements from a list, I want an 
object that looks like a list, however all changes made to that object 
are automagically reflected in the original list. (I guess that is one 
of those 'if it's hard to explain, ...' cases.)

I should have included an example right away ... here goes:

# I have a list
l = [1, 2, 3, 4, 5, 6, 7]

# I then want to create a Filter instance
# (Filter beeing a *class* implemented by me)
# where isEven() returns True whenever an item of l
# should be included in f (in this case, even numbers).
# (I'm asking if something like this exists in the libs
# or elsewhere)
f = Filter(l, isEven)

# The desired behavior now goes something like this:
f
 >>> [2, 4, 6]
del f[1]
f
 >>> [2, 6]
l
 >>> [1, 2, 3, 5, 6, 7]
f.append(77)
f
 >>> [2, 6, 77]
# 77 being intentionally uneven
l
 >>> [1, 2, 3, 5, 6, 7, 77]
# could be [1, 2, 3, 5, 6, 77, 7] as well
# I don't care here

# and so forth ...

I think SQL views are the direct analog.

 > I don't believe it is generic.  Nobody knows your data specs or filtering
 > needs.
Hence the additional function in the Filter constructor ;) . You suggest 
the same thing below, so that is obviously no problem.

 > Use of list comprehension might make it easier to code this:
 >
 > 
I sort of wanted to avoid these. Though my lists shouldn't terribly 
long, so performance is not an issue so much. I simply want to avoid 
having two datasets that I have to sync. Major pain, I believe.


Coding all that really is quite straight forward, but it is a lot of 
mule-work. I hoped (no, I still hope) that there might be somethin like 
that around already.

A bit clearer now?

bye
wildemar
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