Re: Controlling newlines when writing to stdout (no \r\n).
Well, here's the first page turned up by google for the terms 'python binary stdout': http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/65443 Code from that page: import sys if sys.platform == "win32": import os, msvcrt msvcrt.setmode(sys.stdout.fileno(), os.O_BINARY) Thanks, Google & the Python Cookbook website! Jeff pgponre4gehsj.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Octal notation: severe deprecation
On Thu, Jan 13, 2005 at 11:04:21PM +, Bengt Richter wrote: > One way to do it consistently is to have a sign digit as the first > digit after the x, which is either 0 or base-1 -- e.g., +3 and -3 would be > > 2x011 2x101 > 8x03 8x75 > 16x03 16xfd > 10x03 10x97 ... so that 0x8 and 16x8 would be different? So that 2x1 and 2x01 would be different? Jeff pgpSp55b8TgYd.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: directory bug on linux; workaround?
Python is at the whim of the services the OS provides. Maybe you should ask in a linux-related newsgroup or mailing list, they might know more about the specifics of both detecting and working around "weird" filesystems like "fat". To find the type of a filesystem, Linux provides the statfs(2) function, but no built-in Python module includes access to that function. Writing the wrapper would be an easy first exercise in extending Python, or using Pyrex or ctypes. The filesystem "magic numbers" also aren't available in Python. A partial list can be found by "grep _SUPER_MAGIC /usr/include/linux/*" Jeff pgp3igY0cKFnR.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Classical FP problem in python : Hamming problem
Your formulation in Python is recursive (hamming calls hamming()) and I think that's why your program gives up fairly early. Instead, use itertools.tee() [new in Python 2.4, or search the internet for an implementation that works in 2.3] to give a copy of the output sequence to each "multiply by N" function as well as one to be the return value. Here's my implementation, which matched your list early on but effortlessly reached larger values. One large value it printed was 6412351813189632 (a Python long) which indeed has only the distinct prime factors 2 and 3. (2**43 * 3**6) Jeff from itertools import tee import sys def imerge(xs, ys): x = xs.next() y = ys.next() while True: if x == y: yield x x = xs.next() y = ys.next() elif x < y: yield x x = xs.next() else: yield y y = ys.next() def hamming(): def _hamming(j, k): yield 1 hamming = generators[j] for i in hamming: yield i * k generators = [] generator = imerge(imerge(_hamming(0, 2), _hamming(1, 3)), _hamming(2, 5)) generators[:] = tee(generator, 4) return generators[3] for i in hamming(): print i, sys.stdout.flush() pgpDLQcTdYXXo.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Tuple slices
The cpython implementation stores tuples in memory like this: [common fields for all Python objects] [common fields for all variable-size python objects, including tuple size] [fields specific to tuple objects, if any] [array of PyObject*, one for each item in the tuple] This way of storing variable-size Python objects was chosen in part because it reuqires only one allocation for an object, not two. However, there is no way for one tuple to point to a slice of another tuple. there's no reason that some other python implementation couldn't make a different choice. Jeff pgpEIrkTKSDkC.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: tkinter: Can You Underline More Than 1 Char In A Menu Title
On Thu, Jan 27, 2005 at 06:38:22AM -0500, Tim Daneliuk wrote: > Is it possible to underline more than a single character as I am doing > with the 'underline=0' above. I tried 'underline=(0,2)' but that didn't > work. No. Jeff pgpFCNSGSpXA9.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: [Tkinter] problem
These lines
> if __name__ == '__main__':
> OptionsWindow()
mean "if this source code is the main program (not an imported module),
call OptionsWindow()". So the behavior should be different when the
source code is the main program ('python opt_newlogin.py') and when it's
imported ('python -c "import opt_newlogin"')
Jeff
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Re: Embedding Python - Deleting a class instance
I wrote the following module to test the behavior of PyInstance_New. I
called it something like this:
import vedel
class k:
def __del__(self): print "deleted"
vedel.g(k)
I get output like:
after creation, x->refcnt = 1
doing decref
deleted
after decref
Unless there's a cycle and GC gets involved, all there is to deleting
*anything* in Python is correctly managing the refcount. On the other
hand, you can never free an object while it is still reachable. Some
local name "x" may never spontaneously lose the thing it refers to.
/**/
#include
static PyObject *g(PyObject *s, PyObject *o) {
PyObject *x = PyInstance_New( o, NULL, NULL);
if(x) {
printf("after creation, x->refcnt = %d\n", x->ob_refcnt);
printf("doing decref\n");
Py_DECREF(x);
printf("after decref\n");
} else {
printf("x == NULL\n");
}
Py_INCREF(Py_None);
return Py_None;
}
static PyMethodDef methods[] = {
{"g", (PyCFunction)g, METH_O, NULL},
{NULL},
};
void initvedel(void) {
Py_InitModule("vedel", methods);
}
/**/
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Re: eval() in python
On Tue, Jun 21, 2005 at 08:13:47AM -0400, Peter Hansen wrote: > Xah Lee wrote: > > the doc seems to suggest that eval is only for expressions... it says > > uses exec for statements, but i don't seem to see a exec function? > > Because it's a statement: http://docs.python.org/ref/exec.html#l2h-563 but the documentation is sooo baaad that it makes babies cry and maybe spreads herpes too. pgpV9sZIg0dFB.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: utf8 silly question
If you want to work with unicode, then write
us = u"\N{COPYRIGHT SIGN} some text"
You can also write this as
us = unichr(169) + u" some text"
When you have a Unicode string, you can convert it to a particular
encoding stored in a byte string with
bs = us.encode("utf-8")
It's generally a mistake to use the .encode() method on a byte string,
but that's what code like
bs = "\xa9 some text"
bs = bs.encode("utf-8")
does. It can lull you into believing it works, if the test data only
has US ASCII contents, then break when you go into production and have
non-ASCII strings.
Jeff
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Re: PEP ? os.listdir enhancement
Why not just define the function yourself? Not every 3-line function needs to be built in. def listdir_joined(path): return [os.path.join(path, entry) for entry in os.listdir(path)] dirs = [x for x in listdir_joined(path) if os.path.isdir(x)] path_size = [(x, getsize(x)) for x in listdir_joined(path) if os.path.isfile(x)] Jeff pgpwXvnkgy6r4.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Loop until condition is true
def until(pred): yield None while True: if pred(): break yield None def example(): i = 0 for _ in until(lambda: x==0): x = 10 - i i += 1 print x, i example() pgpeP7iW6mcQm.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Is this a bug? I don't know where to start
Your list "targets" contains some values twice. >>> targets=[97,101,139,41,37,31,29,89,23,19,8,13,131,19,73,97,19,139,79,67,61,17,113,127] >>> for t in set(targets): ... if targets.count(t) > 1: print t ... 97 139 19 It looks like the "duplicated" items in the output contain one of the duplicated items from the input. Jeff pgpqzHdpM3xQ3.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Frame widget (title and geometry)
It would help if you posted your code, as we're in the dark about exactly what you tried to do and the error you received. It sounds like you may be using the wrong type of widget for what you want. The terms used in Tk are different than in some other systems. If you want a separate window with title bar etc, you want to create a new instance of Tkinter.Toplevel. It will have methods like wm_title and wm_geometry. Newer versions of Tk (8.4 and maybe 8.3) have a widget called "labelframe" (called Tkinter.LabelFrame in python2.3 and newer) which is the grooved-border-and-label container used to semantically group related widgets. "Frame" widgets are simply containers which are often useful for making the screen layout work the way you want with pack and grid. Jeff pgpdBiMtDJV5v.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Frame widget (title and geometry)
Tkinter.Frame instances are not created with "geometry" or "title" attributes. Whatever 'classtitle' and 'classtitle2' are, they are not written to work with Tkinter.Frame instances. Jeff pgppDkXNnBRVL.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Beginner question: Converting Single-Element tuples to list
On Mon, Jun 27, 2005 at 08:21:41AM -0600, John Roth wrote: > Unfortunately, I've seen that behavior a number of times: > no output is None, one output is the object, more than one > is a list of objects. That forces you to have checks for None > and list types all over the place. maybe you can at least push this into a single convenience function... def destupid(x, constructor=tuple, sequencetypes=(tuple, list)): if x is None: return constructor() if isinstance(x, sequencetypes): return x return constructor((x,)) Jeff pgpC9L79OCj2p.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Dictionary to tuple
It looks like you want tuple(d.iteritems())
>>> d = {1: 'one', 2: 'two', 3: 'three'}
>>> tuple(d.iteritems())
((1, 'one'), (2, 'two'), (3, 'three'))
You could also use tuple(d.items()). The result is essentially the
same. Only if the dictionary is extremely large does the difference
matter. (or if you're using an older version of Python without the
iteritems method)
Jeff
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Re: It seems that ZipFile().write() can only write files, how can empty directories be put into it?
This has been discussed before. One thread I found was http://mail.python.org/pipermail/python-list/2003-June/170526.html The advice in that message might work for you. Jeff pgpPSqdIxsPgx.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Trapping user logins in python ( post #1)
I don't know of a portable way for an inetd-style daemon to "listen" for user logins. On some systems (including RedHat/Fedora and debian), you may be able to use PAM to do this. (pam modules don't just perform authentication, they can take other actions. As an example, pam_lastlog "prints the last login on successful login". I'm not sure what priviledge a pam module has when it executes. A more standard way to do this would be to place lines in /etc/profile /etc/csh.login and so forth for any other shells used on your system. RedHat-style systems have an /etc/profile.d where you can drop a file that will be executed at login, too. This will, of course, be executed with the user's privilege level. Another problem with this approach is that /etc/profile is executed for a "login shell", but a graphical login is not a login shell. Jeff pgpaiKK6vpl7N.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: importing pyc from memory?
This stupid code works for modules, but not for packages. It probably has bugs.
import marshal, types
class StringImporter:
def __init__(self, old_import, modules):
self._import = old_import
self._modules = modules
def __call__(self, name, *args):
module = self._modules.get(name, None)
if module is None:
return self._import(name, *args)
code = marshal.loads(module)
mod = types.ModuleType(name)
exec code in mod.__dict__
return mod
def test():
import __builtin__
__builtin__.__import__ = StringImporter(__builtin__.__import__,
{ 'test_importer': open("/usr/lib/python2.3/os.pyc").read()[8:] })
import test_importer
print test_importer.path.join("a", "b")
print test_importer.__doc__
if __name__ == '__main__': test()
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Re: Tkinter + Tcl help
I think you need to write
root.tk.eval('load', '...\\libtcldot.so.0')
When you write
root.tk.eval("x y z")
it's like doing this at the wish/tclsh prompt:
# {x y z}
Not like this:
# x y z
Now, how useful it is to have a command called "x y z", I can't
guess... but tcl would let you do it.
I've also doubled the backslash in your library filename. When using
windows-style paths in string literals, you must either double the
backslashes, or use r'' strings. When you don't, it will often work,
but if the character after the un-doubled backslash is one with special
meaning (including the commonly-seen \r and \t, but also other letters)
then you'll get a pathname and an error that leave you scratching your
head.
Jeff
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Re: resume upload
probably by using REST. This stupid program puts a 200 line file by
sending 100 lines, then using REST to set a resume position and sending
the next 100 lines.
import getpass, StringIO, ftplib
lines = ["Line %d\n" % i for i in range(200)]
part1 = "".join(lines[:100])
part2 = "".join(lines[:100])
f = ftplib.FTP('server', 'username', 'password')
f.debugging = True
f.sendcmd('CWD /tmp')
f.storbinary("STOR example", StringIO.StringIO(part1))
f.putcmd('REST %d' % len(part1))
resp = f.getresp();
if resp[0] != '3': raise ftplib.error_reply, resp
f.storbinary("STOR example", StringIO.StringIO(part2))
f.quit()
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Re: math.nroot [was Re: A brief question.]
On Tue, Jul 05, 2005 at 09:49:33PM +0100, Tom Anderson wrote: > Are there any uses for NaN that aren't met by exceptions? Sure. If you can naturally calculate two things at once, but one might turn out to be a NaN under current rules. x, y = calculate_two_things() if isnan(x): perform_next_step_with_only_y(y) else: perform_next_step_with_both(x, y) Under your scheme, you'd have to write try: x, y = calculate_two_things() except NaNException: y = calculate_one_thing() perform_next_step_with_only_y(y) else: perform_next_step_with_both(x, y) and at the very least duplicate the code for calculating 'y', possibly re-doing a lot of work at runtime too. Jeff pgpVUpJh4xufX.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Strange os.path.exists() behaviour
Pierre wrote:
> Python 2.4 (#60, Nov 30 2004, 11:49:19) [MSC v.1310 32 bit (Intel)] on win32
^^^
Here's the bug. You're using Windows. It's a filesystem, but not as we know
it...
Anyway, You are getting exactly what the low-level Windows APIs return.
Here's a small "C" program. It prints "0" next to the filename if the
file exists, -1 otherwise, as described at
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vclib/html/_crt__access.2c_._waccess.asp
int main(int argc, char **argv) {
int i;
for(i=1; idir
Volume in drive C has no label.
Volume Serial Number is 171D-4D2A
Directory of C:\TMP\example
07/06/05 03:04p .
07/06/05 03:04p ..
07/06/05 03:05p 3 exist
3 File(s) 3 bytes
C:\TMP\example>x:a.exe exist exist. exist nonexist nonexist. nonexist...
exist: 0
exist.: 0
exist: 0
nonexist: -1
nonexist.: -1
nonexist...: -1
C:\TMP\example>type nonexist
The system cannot find the file specified.
C:\TMP\example>type exist
C:\TMP\example>
As you can see, not only does Windows think that "exist" exists, but it can
successfully "type" its contents too!
Jeff
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Re: Query
python-xlib includes an implementation of the xtest extension, which is enabled on most users' X servers, and can be used to send arbitrary keyboard or mouse events. jeff pgpo7pqhBafPe.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: About undisclosed recipient
You provided far too little information for us to be able to help. If you are using smtplib, it doesn't even look at message's headers to find the recipient list; you must use the rcpt() method to specify each one. If you are using the sendmail method, the "to_addrs" list has no relationship to the headers of the actual message---it simply calls rcpt() once for each address in to_addrs. The example in the docstring doesn't even *have* a To: header in the message! Jeff pgpHNq6sWEuR7.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: cursor positioning
Here's a simple module for doing progress reporting. On systems without
curses, it simply uses "\r" to return the cursor to the first column.
On systems with curses, it also clears to the end of the line. This
means that when the progress message gets shorter, there aren't droppings
left from the longer ones.
You have to take care that the progress message isn't wider than the
screen, but I don't know a nice way to *find* the width of the screen
that will work on windows and unix. Hardcoding 80 ain't it either.
import sys
def progress(s):
sys.stderr.write(s + CLEAR_EOL + "\r"); sys.stderr.flush()
try:
import curses
except ImportError:
CLEAR_EOL = ''
else:
curses.setupterm()
CLEAR_EOL = curses.tigetstr("el") or ''
def test():
import time
for j in range(2):
for i in range(100):
progress("Doing item %d, %d%%" % (i * 100, i))
time.sleep(.01)
if __name__ == '__main__': test()
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Re: Parsing Data, Storing into an array, Infinite Backslashes
Your code is needlessly complicated.
Instead of this business
while 1:
try:
i = fetch.next()
except stopIteration:
break
simply write:
for i in fetch:
(if there's an explicit 'fetch = iter(somethingelse)' in code you did
not show, then get rid of that and just loop 'for i in somethingelse')
i[1] will never compare equal to count, because i[1] is always a string
and count is always an integer. Integers and strings are never equal to
each other.
Wring code like
x = "a string " + 3
does not work in Python. You can either convert to a string and then
use the + operator to concatenate:
x = "a string " + str(3)
or you can use %-formatting:
x = "a string %s" % 3
("%s" accepts any sort of object, not just strings)
Using repr(...) (`...` is just a shorthand for this) is what is really
introducing the backslashes. When it outputs a string, it quotes the
string using backslashes. But you pass the old part of the prepared
string through it each time, which leads to doubling backslashes.
Below is a program I wrote to process the data in your message. It prints
out
Memory 2 Summary=0, Speed=PC3200U-30330, Type=DDR SDRAM, Size=512,
Slot=DIMM2/J13, ConfigurationType=2
Memory 3 Summary=0, Speed=PC3200U-30330, Type=DDR SDRAM, Size=512,
Slot=DIMM3/J14, ConfigurationType=2
Memory 0 Summary=0, Speed=PC3200U-30330, Type=DDR SDRAM, Size=512,
Slot=DIMM0/J11, ConfigurationType=2
Memory 1 Summary=0, Speed=PC3200U-30330, Type=DDR SDRAM, Size=512,
Slot=DIMM1/J12, ConfigurationType=2
the result is out of order because the result of calling .items() on a
dict is in an arbitrary order.
Jeff
s = [['Memory', '0', 'Summary', '0'], ['Memory', '0', 'Speed',
'PC3200U-30330'], ['Memory', '0', 'Type', 'DDR SDRAM'], ['Memory', '0',
'Size', '512'], ['Memory', '0', 'Slot', 'DIMM0/J11'], ['Memory', '0',
'ConfigurationType', '2'], ['Memory', '1', 'Summary', '0'], ['Memory',
'1', 'Speed', 'PC3200U-30330'], ['Memory', '1', 'Type', 'DDR SDRAM'],
['Memory', '1', 'Size', '512'], ['Memory', '1', 'Slot', 'DIMM1/J12'],
['Memory', '1', 'ConfigurationType', '2'], ['Memory', '2', 'Summary',
'0'], ['Memory', '2', 'Speed', 'PC3200U-30330'], ['Memory', '2',
'Type', 'DDR SDRAM'], ['Memory', '2', 'Size', '512'], ['Memory', '2',
'Slot', 'DIMM2/J13'], ['Memory', '2', 'ConfigurationType', '2'],
['Memory', '3', 'Summary', '0'], ['Memory', '3', 'Speed',
'PC3200U-30330'], ['Memory', '3', 'Type', 'DDR SDRAM'], ['Memory', '3',
'Size', '512'], ['Memory', '3', 'Slot', 'DIMM3/J14'], ['Memory', '3',
'ConfigurationType', '2']]
query = {}
for a, b, c, d in s:
if not query.has_key((a,b)): query[(a,b)] = []
query[(a,b)].append("%s=%s" % (c, d))
for (a,b), v in query.items():
print a, b, ", ".join(v)
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Re: Browser plug-in for Python?
Back in the day there was 'grail', which was a browser in its own right. There may also have been a plug-in for other browsers, but I don't know any real details about them. Python itself has deprecated the 'restricted execution' environment it had in previous versions, because ways to break out of the jail existed or were thought to exist, and nobody stepped forward and offered to spend the requisite time to create and validate (even in a hand-wavy kind of way) a new security model. If you want to write programs in Python and run them in today's browsers, the shortest path from here to there is jython. Several applet demos are available at http://www.jython.org/applets/index.html I have used Jython a little bit, but never seriously and not in the past few years. Jython implements an older version of the Python language, corresponding to cPython 2.1 if I remember correctly. Jeff pgpp6YhsWNcK0.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: ssh popen stalling on password redirect output?
In your ssh configuration, specify something like PreferredAuthentication "hostbased,publickey" this will skip trying to use the methods called keyboard-interactive and password. You can give this flag on the ssh commandline, too. read the ssh(1) and ssh_config(5) manpages for more information. Jeff pgpYxuAq33BRa.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: stdin/stdout fileno() always returning -1 from windows service
On Sun, Jul 17, 2005 at 06:43:00PM -0700, chuck wrote:
> I have found that sys.stdin.fileno() and sys.stdout.fileno() always
> return -1 when executed from within a win32 service written using the
> win32 extensions for Python.
>
> Anyone have experience with this or know why?
because there *is* no standard I/O for a windows service.
You should be able to execute code like
import sys
sys.stdout = sys.stderr = open("some.log", "w")
if you have code that expects the standard output files to be available.
You could also open sys.stdin in a similar way.
Jeff
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Re: stdin/stdout fileno() always returning -1 from windows service
It seems to simply be common wisdom. e.g., http://mail.python.org/pipermail/python-win32/2004-September/002332.html http://mail.mems-exchange.org/pipermail/quixote-users/2004-March/002743.html http://twistedmatrix.com/pipermail/twisted-python/2001-December/000644.html etc If you can find chapter and verse on MSDN, more power to you. This page implies that the "standard handles" are only available when there is a console for the application. http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dllproc/base/getstdhandle.asp Jeff pgpD1VX32k6bY.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Windows command line problem
I don't exactly know what is going on, but '\x96' is the encoding for
u'\N{en dash}' (a character that looks like the ASCII dash,
u'\N{hyphen-minus}', u'\x45') in the following windows code pages:
cp1250 cp1251 cp1252 cp1253 cp1254
cp1255 cp1256 cp1257 cp1258 cp874
Windows is clearly doing something clever.
Jeff
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Re: Opinions on KYLIX 3 (Delphi 4 Linux)
I honestly don't know why anyone would spend money for a development environment, no matter how fancy. I don't know why anyone would develop software in a language that doesn't have at least one open implementation. It's a great way to get screwed when Borland goes under or decides they only want to sell a new, incompatible product. What do you do with your existing product when that happens? Re-train on a new platform, and re-write from scratch? Just say no to proprietary software. Jeff pgpiV5WmgG2I1.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Image orientation and color information with PIL?
>>> i = Image.open("blue.jpg")
>>> i.size
(3008, 2000)
>>> i.mode
'RGB'
'RGB' is the value for color jpeg images. I believe that for black&white
images, i.mode is 'L' (luminosity).
If you want to determine whether an existing image is landscape or portrait,
then just compare i.size[0] (width) and i.size[1] (height).
If by "determine if an image is horizontal/vertical", you want to find
the orientation data recorded by some digital cameras, you can do that
with PIL 1.1.4. According to the release notes for 1.1.4,
+ Added experimental EXIF support for JPEG files. To extract EXIF
information from a JPEG file, open the file as usual, and call the
"_getexif" method. If successful, this method returns a dictionary
mapping EXIF TIFF tags to values. If the file does not contain EXIF
data, the "_getexif" method returns None.
The "ExifTags" module contains a dictionary mapping tags to tag
names.
This interface will most likely change in future versions.
The exif tag 274 is Orientation. The values you'll see most often are 1
(Normal), 6 and 8 (90 and 270 degree rotations). Orientation can also encode
180 degree rotation, as well as any of the four rotations combined with a
mirror operation.
>>> [k for (k,v) in ExifTags.TAGS.items() if v == 'Orientation']
[274]
>>> e = i._getexif()
>>> if e: print e[274]
1
I have written a standalone Python module that reads and changes the EXIF
orientation data. You can view it here:
http://unpy.net/cgi-bin/viewcvs.cgi/aethertool/disorient.py?rev=1.2&content-type=text/vnd.viewcvs-markup
It is available under the terms of the GNU GPL.
Here's another page about EXIF orientation data:
http://sylvana.net/jpegcrop/exif_orientation.html
Jeff
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Re: Image orientation and color information with PIL?
On Mon, Jul 18, 2005 at 10:55:42AM -0600, Ivan Van Laningham wrote: > How are you going to determine the orientation of an image without > sophisticated image analysis? There is research on automatic image > orientation detection. [...] > If you write it I'll use it;-) There's research going on in this area. Here are a few papers: http://www.dcs.shef.ac.uk/teaching/eproj/msc2004/abs/m3zs2.htm http://research.microsoft.com/research/pubs/view.aspx?pubid=918 there are probably many others. I considered implementing one of these algorithms back in 2003 or so, but instead I bought a digital camera with an orientation sensor. Jeff pgpJZsejWH68l.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Filling up commands.getstatusoutput's buffer
On Wed, Jul 20, 2005 at 03:10:49PM -0700, [EMAIL PROTECTED] wrote:
> Hey,
>
> Has anyone ever had commands.getstatusoutput's buffer fill up when
> executing a verbose command? [...]
How much output are you talking about? I tried outputs as large as
about 260 megabytes without any problem. (RedHat 9, Python 2.2)
>>> len(commands.getoutput("dd if=/dev/zero bs=512 count=512000 2>/dev/null"))
262144000
>>> 512 * 512000
262144000
Jeff
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Re: time.time() under load between two machines
What makes you believe that the two machines' clocks are perfectly
synchronized? If they're not, it easily explains the result.
I wrote a simple client/server program similar to what you described.
Running on two RedHat 9 machines on a local network, I generally
observed a time delta of 2ms (compared to typical 0.17ms latency
reported by "ping"), never in a negative direction. These machines
times are synchronized by ntpd from the package ntp-4.1.2-0.rc1.2.
My program can be run like this:
rsh otherhost python timely.py -s | python timely.py -r
the values printed are the difference between the remote time before the
message is sent and the local time after the message is received.
You mention using Windows. I don't know whether Windows machines by
default use anything as sophisticated as ntpd to keep their clocks
accurate.
Whatever is going on in your case, I suspect it is the operating system,
not Python.
Jeff
import os, sys, time
def serve():
while 1:
data = struct.pack("!d", time.time())
os.write(1, data)
time.sleep(1)
def recv(fileno):
while 1:
data = struct.unpack("!d", os.read(fileno, 8))[0]
now = time.time()
print now - data
if sys.argv[1] == "-s":
serve()
else:
recv(0)
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Re: Mapping a drive to a network path
import os os.system(r"net use z: \\computer\folder") Something in the win32net module of win32all may be relevant if you don't want to do it through os.system: http://aspn.activestate.com/ASPN/docs/ActivePython/2.4/pywin32/win32net__NetUseAdd_meth.html Jeff pgp7mEoPdAfNP.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Mapping a drive to a network path
in fact, see this thread, it may have something useful for you: http://mail.python.org/pipermail/python-win32/2003-April/000959.html Jeff pgprYPOH3yOyI.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Getting TypeError in Changing file permissions
If you are using Unix, and all you have is the file object, you can use os.fchmod(outfile.fileno(), 0700) Jeff pgp8U05e26RUt.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Question about namespaces and import. How to avoid calling os.system
In main.py, execfile("gen.py")
or
In gen.py, have something like
from __main__ import env_params
or
In main.py, have something like
import __builtins__; __builtins__.env_params = env_params
or
call a function in the gen.py with env_params as a parameter
import gen
gen.do(env_params)
Jeff
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Re: How to realize ssh & scp in Python
Rather than doing anything with passwords, you should instead use public key authentication. This involves creating a keypair with ssh_keygen, putting the private key on the machine opening the ssh connection (~/.ssh/id_rsa), then listing the public key in the remote system's ~/.ssh/authorized_keys. If you don't want to use this approach, `pexpect'[1] is supposed to be able to perform this sort of tasks, and one of its examples is called `sshls.py'. I just downloaded it, and after changing the ssh commandline to include -o 'PreferredAuthentications password' it worked for me. In another recent thread, a different poster claimed it didn't work, so your results may vary. Jeff [1] http://pexpect.sourceforge.net/ pgprScaQubqXA.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Tkinter - Resizing a canvas with a window
You should just use 'pack' properly. Namely, the fill= and expand= parameters. In this case, you want to pack(fill=BOTH, expand=YES). For the button, you may want to use pack(anchor=E) or anchor=W to make it stick to one side of the window. The additional parameters for the button (both creation and packing) give a geometry that is closer to the standard buttons in Windows 95 / Windows 2000. Use those or not, as you see fit. Here's the new program: from Tkinter import * class testApp2: def __init__( self, master ): self.ma = master self.f = Frame( self.ma ) self.f.pack(fill=BOTH, expand=YES) self.cv = Canvas(self.f, width=25, height=25, bg='red') self.cv.pack(fill=BOTH, expand=YES) self.b1 = Button( self.f, text='Hello', height=1, width=10, padx=0, pady=1) self.b1.pack(side=BOTTOM, anchor=E, padx=4, pady=4) root = Tk() app = testApp2(root) root.mainloop() Jeff PS thanks for including a full, runnable program in your post! pgpqy4uUUgiLH.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Stripping C-style comments using a Python regexp
#
import re, sys
def q(c):
"""Returns a regular expression that matches a region delimited by c,
inside which c may be escaped with a backslash"""
return r"%s(\\.|[^%s])*%s" % (c, c, c)
single_quoted_string = q('"')
double_quoted_string = q("'")
c_comment = r"/\*.*?\*/"
cxx_comment = r"//[^\n]*[\n]"
rx = re.compile("|".join([single_quoted_string, double_quoted_string,
c_comment, cxx_comment]), re.DOTALL)
def replace(x):
x = x.group(0)
if x.startswith("/"): return ' '
return x
result = rx.sub(replace, sys.stdin.read())
sys.stdout.write(result)
#
The regular expression matches ""-strings, ''-character-constants,
c-comments, and c++-comments. The replace function returns ' ' (space)
when the matched thing was a comment, or the original thing otherwise.
Depending on your use for this code, replace() should return as many
'\n's as are in the matched thing, or ' ' otherwise, so that line
numbers remain unchanged.
Basically, the regular expression is a tokenizer, and replace() chooses
what to do with each recognized token. Things not recognized as tokens
by the regular expression are left unchanged.
Jeff
PS this is the test file I used:
/* ... */ xyzzy;
456 // 123
const char *mystr = "This is /*trouble*/";
/* * */
/* /* */
// /* /* */
/* // /* */
/*
* */
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Re: codecs.getencoder encodes entire string ?
On Thu, Jul 28, 2005 at 08:42:57AM -0700, nicolas_riesch wrote: > And a last question: can I call this "enc" function from multiple > threads ? Yes. Jeff pgphSka1eU9PQ.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: poplib.POP3.list() returns extra value?
With a judicious bit of UTSL, that count seems to be the total number of octets in the reply. This information comes from any user of _getlongresp(), which actually returns a tuple (resp, list, octets). These methods would be: list retr top uidl I'd consider it a doc bug too. If you feel comfortable doing it, dive in and improve the documentation of poplib. Submitting a patch to the patch tracker on sf.net/projects/python is probably the best way to do this, if you have the necessary knowledge of cvs to produce a patch. Jeff pgpR6zOckMUPS.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: A replacement for lambda
On Fri, Jul 29, 2005 at 10:14:12PM -0700, Tim Roberts wrote: > C++ solves this exact problem quite reasonably by having a greedy > tokenizer. Thus, that would always be a left shift operator. To make it > less than and a function, insert a space: > < Incidentally, I read in an article by Bjarne Stroustrup[1] that "C++0x" will parse vector> v; just like today's compilers parse vector > v; Another of the changes he discusses, letting 'auto i = ...' create i with the type of the expression '...', will certainly be an improvement. Even better if the keyword 'auto' could be made optional! (Of course, this is another break with C, where the declaration auto i; makes 'i' an int) And what's this got to do with Python? I dunno. Sorry. Jeff [1] http://www.informit.com/content/images/art_stroustrup_2005/elementLinks/rules.pdf pgpmO2bTojrLg.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Newb: Telnet 'cooked data','EOF' queries.
On Sun, Jul 31, 2005 at 01:30:43PM +0100, glen wrote: > Could someone explain what "cooked data" is. The telnet protocol contains special sequences which are interpreted by the telnet client or server program. These are discussed in the telnet RFC, which is RFC854 according to the telnetlib docstring. "Cooked" data is data after these special sequences are removed. > Also when trying read_all() the program seems to lock up, which I assume > is because it is waiting for an EOF, but 'when' is an EOF received. As far as I know, the only EOF in telnet is when the other side closes the socket. Jeff pgpnCbDvhyN27.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Getting not derived members of a class
On 'y', Python has no way of recording where '_a' and '_b' were set, so
you can't tell whether it comes from class 'a' or 'b'.
You can find the attributes that are defined on 'b' only, though, by
using 'b.__dict__.keys()', or 'y.__class__.__dict__.__keys__()'. This
gives
['__module__', 'who1', '__init__', '__doc__']
If you want to limit yourself to current versions of cpython (because the
bytecode used in cpython is only an implementation detail) and define a 'member
of class a' as one where a.__init__ has a statement like 'self.z = ...', you
can peer into the bytecodes. Something like this:
from dis import HAVE_ARGUMENT, opname
LOAD_FAST = chr(opname.index('LOAD_FAST'))
STORE_ATTR = chr(opname.index('STORE_ATTR'))
HAVE_ARGUMENT = chr(HAVE_ARGUMENT)
def find(cls):
ns = cls.__dict__
result = ns.keys()
init = ns.get('__init__', None)
if not init: return ns
f = ns['__init__'].func_code.co_code
n = ns['__init__'].func_code.co_names
i = 0
while i < len(f) - 6:
if (f[i] == LOAD_FAST and f[i+1] == f[i+2] == '\0'
and f[i+3] == STORE_ATTR):
j = ord(f[i+4]) + 256 * ord(f[i+5])
result.append(n[j])
i += 6
elif f[i] > HAVE_ARGUMENT:
i += 3
else:
i += 1
return result
>>> import franz
>>> franz.find(y.__class__)
['__module__', 'who1', '__init__', '__doc__', '_b']
Jeff
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Re: [noob] Questions about mathematical signs...
On Sun, Feb 06, 2005 at 12:26:30PM -0800, administrata wrote: > Hi! I'm programming maths programs. > And I got some questions about mathematical signs. > > 1. Inputing suqare like a * a, It's too long when I do time-consuming >things. Can it be simplified? You can write powers with the "**" operator. In this case, a ** 2 > 2. Inputing fractions like (a / b) + (c / d), It's tiring work too. >Can it be simplified? Because of the rules of operator precedence, a / b + c / d has the same meaning as the expression you gave. > 3. How can i input root? Assuming that you've already executed import math Here are some ways to find the square root of a number: math.sqrt(4) 4 ** .5 math.pow(4, .5) Jeff pgpUKyYywumMf.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Is Python as capable as Perl for sysadmin work?
No. Unlike Perl, Python implements only a *finite turning machine* model of computation. An easy way to see this limitation is in the following code: >>> 1.0 / 10.0 0.10001 In an infinite Turning machine, there would be an unbounded number of zeros before the second 1, giving the exact result, not a numeric approximation. There's another little-known fact about Python: No string is permitted to end with a backslash! You might think that variations like r'\' or ""\"" would allow you to create this elusive value, but you'd mistaken! Now, this may not bother Unix sysadmins, but the honest truth is that you'll be administrating Windows systems, too, anywhere you work! Finally, Python just doesn't respond to threats as well as Perl does. I have run into many Perl programs that just didn't quite work right until I wrote '... or die "$!"' in the right places. Well, if you ever have to threaten Python, just keep in mind that '... or die' just plain won't work. You have to suggest that it 'try ... except', which is really offensive. If I want to beg my computer to run programs, I know where to find Intercal with its "PLEASE" and "DO PLEASE" constructions. Jeff pgpmDM5lPWYOK.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Tkinter.Canvas saved as JPEG?
The Tkinter Canvas directly supports saving to postscript format, but not any standard bitmap format (or even modern vector formats like pdf or svg). Jeff pgpBVvDhXslRq.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: exec function
In this case, you can use getattr() instead of the exec statement: getattr(self.frame, t).SetTable(DataTable(d, r[0]), True) Jeff pgp6KrffC7xJf.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Why Tk treat F10, F11, F12 diferently from F1...F9?
The reason that F10 does nothing is because there is already a binding
on all for . In Motif apps, F10 moves focus to the menu bar, like
pressing and releasing Alt does on Windows. When there is a binding for
a key, the handling of the event "event add" never takes place.
If you want to get rid of this binding, you would do it with something
like
w.bind_all("", "")
for some widget w.
I don't know why you see the "L1" and "L2" keysyms. I don't on my
system (Fedora Core 2)
Jeff
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Re: SCons build tool speed
On Sun, Feb 13, 2005 at 08:39:10PM -0500, Peter Hansen wrote:
> That answer, combined with Mike's response pointing out
> that tools more sophisticated than basic "make" actually
> can delve into the source and identify the dependencies,
Argh argh argh.
Of course you can write a makefile to "delve into the source and
identify the dependencies". And, by the way, there's no need for make
to be recursive when a project spans multiple directories. (the other
popular misconception about make)
Below is a GNU makefile that I use to build a small program. I
re-organized the file a bit before posting to clearly separate the two
sections of the makefile, and it's possible I broke something in the
process.
Since my system has subsecond file timestamps and I do not build with source
or object files on network filesystems, the "timestamp comparison"
method works just fine to decide whether a target must be rebuilt or
not.
What programs like SCons *do* is include nice built-in definitions of
stuff like the 'obj/%.d: %.cc' rule (often with a built-in parser which
you can bet will not be 100% compatible with your compiler!), built-in
inclusion of dependency lists with no extra programmer action, and the
features I don't need like the use of cryptographic hashes to compare
files.
A larger system I work on uses GNU make to build around 6000 object
files into a single executable. A "do-nothing" make takes around 8
seconds on a 2.8GHz machine. This involves parsing about 6000 lines of
Makefiles and Submakefiles (per-directory lists of source files), and
about 650klines of dependency information.
I don't know how this measures up to "modern" tools like SCons. I'd be
curious to know.
But it's my opinion that a well-designed "make library" and/or "make
preprocessor" to go with GNU Make would be right up there with SCons in
its "power", while avoiding the need for a tool that most people have
never heard of and don't already have installed on their system (yes, a
pretty Linux-centric view).
One criticism of Make that I'd take seriously is that it's a
domain-specific language and usually I say those are terrible ideas. I
still have to refer to the manual to remember which of $*, $@, $^ or $<
I need, sometimes, even though I've been a GNU Make power user for two
years now.
Jeff
#
# This section of the makefile names the source files (one in this case)
# and other complier options. It also has a rule for linking the target
# program
default: stippler
LFLAGS := -L/usr/X11R6/lib
LIBS := -lGL -lGLU -lglut -lXi -lXmu -lX11 -lm -lnetpbm
SRCS := main.cc
CFLAGS := -mcpu=pentium4 -O0 -g -DOUTPUT_POSTSCRIPT
stippler: $(OBJS)
$(CCLD) $(LFLAGS) -o $@ $^ $(LIBS)
#
# This section, which is essentially boilerplate, says how to generate
# the list of dependencies or the object file from a given source file.
# It also transforms the list of sources into a list of objects, and
# includes all the necessary dependency lists ("dot d files")
#
# The definition of OBJS would be more complex if source files of
# different types exist (.c and .cc files, for example)
OBJS := $(patsubst %.cc, obj/%.o, $(SRCS))
CCLD := $(CC)
include $(patsubst %.o,%.d,$(OBJS))
obj/%.d: %.cc
mkdir -p $(dir $@)
$(CC) -MM -MG -MT "$@ $(patsubst obj/%.d,obj/%.o,$@)" \
$(CFLAGS) $< -o [EMAIL PROTECTED] && mv -f [EMAIL PROTECTED] $@
obj/%.o: %.cc
$(CC) $(CFLAGS) -c $< -o [EMAIL PROTECTED] && mv -f [EMAIL PROTECTED] $@
#
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Re: 64 bit Python
There's not enough information to guess the "real problem", but it could be this: "variable size" objects (declared with PyObject_VAR_HEAD) are limited to INT_MAX items since the ob_size field is declared as 'int'. This means that a Python string, tuple, or list (among other types) may be limited to about 2 billion items on ILP32 and LP64 architectures. Dicts and probably sets are also limited to INT_MAX elements, because the "ma_fill" and "ma_used" fields are ints. If you don't mind recompiling all your extensions, you could change the type of ob_size to long in the "#define PyObject_VAR_HEAD". I don't know what breaks when you do this, but maybe a few google or google groups searches could help you find others who have tried this. Jeff PS the limit of 500MB of "real data" in the 32-bit system may be because a realloc may temporarily require (old size + new size) storage when it does the equivalent of new_ptr = malloc(new_size) memcpy(new_ptr, old_ptr, old_size) free(old_size) which will temporarily use >900MB of data when resizing a ~450MB object. Python frequently uses realloc() to grow structures like lists. If you are working with strings, then s = s + t doesn't ever use realloc (in 2.3.x anyway) but always allocates and fills the result 's+t', only freeing the old value of s later when it is no longer reacahable (which could be as soon as the assignment statement completes) pgp7QRCaTXJkk.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: [Errno 18] Invalid cross-device link using os.rename
mv is a surprisingly complex program, while os.rename is a wrapper
around rename(2) which is probably documented on your system to return
EXDEV under these circumstanes.
os.xxx is generally a fairly thin wrapper around what your OS provides,
and inherits all the "gotchas". For some activities, os.shutil provides
something that is between os.xxx and os.system("xxx") in complexity and
capability.
Jeff
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Re: How can I tell if my host supports Python?
If you have a shell, it's as simple as typing "python" and seeing if the interactive interpreter appears: $ python Python 2.3.3 (#1, May 7 2004, 10:31:40) [GCC 3.3.3 20040412 (Red Hat Linux 3.3.3-7)] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> If you've done this, you can find out the path to this Python interpreter: >>> import sys; print sys.executable /usr/bin/python Otherwise, the documentation for the 'cgi' module has a buried suggestion with the simplest Python CGI program. http://docs.python.org/lib/node462.html that program would look something like #!/usr/bin/python import cgi; cgi.test() though you must know the correct path to the Python interpreter for this to work. Your best bet may be to ask your webhost for help---only they know how they've (mis)configured your system. Jeff pgpX2kl4Q6m04.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: super not working in __del__ ?
When a Python program exits, various steps of cleanup occur. One of them is that each entry in the __dict__ of each module is set to 'None'. Imagine that your __del__ runs after this step of the cleanup. The reference to the module-level variable that names your class is no longer available I looked around at the documentation and didn't immediately find where this is documented. The closest I saw was in the C API reference: void Py_Finalize( ) Undo all initializations made by Py_Initialize() and subsequent use of Python/C API functions, and destroy all sub-interpreters (see Py_NewInterpreter() below) that were created and not yet destroyed since the last call to Py_Initialize(). Ideally, this frees all memory allocated by the Python interpreter. This is a no-op when called for a second time (without calling Py_Initialize() again first). There is no return value; errors during finalization are ignored. This function is provided for a number of reasons. An embedding application might want to restart Python without having to restart the application itself. An application that has loaded the Python interpreter from a dynamically loadable library (or DLL) might want to free all memory allocated by Python before unloading the DLL. During a hunt for memory leaks in an application a developer might want to free all memory allocated by Python before exiting from the application. * Bugs and caveats: The destruction of modules and objects in modules is * done in random order; this may cause destructors (__del__() methods) to * fail when they depend on other objects (even functions) or modules. Dynamically loaded extension modules loaded by Python are not unloaded. Small amounts of memory allocated by the Python interpreter may not be freed (if you find a leak, please report it). Memory tied up in circular references between objects is not freed. Some memory allocated by extension modules may not be freed. Some extensions may not work properly if their initialization routine is called more than once; this can happen if an application calls Py_Initialize() and Py_Finalize() more than once. but this doesn't go into detail about exactly how modules are cleaned up. If anybody knows if this is better-documented somewhere, please speak up! Jeff pgpQsq77lVQfz.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Attaching to a Python Interpreter a la Tcl
Cameron Laird mentioned Tk's send working with Python; if you are writing your
app with Tkinter, here is some code to let you use tcl commands like
send python
for remote control. You could build a more sophisticated front-end for this,
and you'll probably also want to add stuff like sending the text of an
exception as the result of the 'send' command.
Jeff
#
import Tkinter
__all__ = 'python', 'setup_send'
def makecommand(master, name, func, subst=None, needcleanup=0):
f = Tkinter.CallWrapper(func, subst, master).__call__
master.tk.createcommand(name, f)
if needcleanup:
if master._tclCommands is None:
master._tclCommands = []
master._tclCommands.append(name)
return name
def setup_send(app, ns, name="python"):
def python(*args):
s = " ".join(args)
print args
try:
code = compile(s, '', 'eval')
return eval(code, ns)
except SyntaxError:
code = compile(s, '', 'exec')
exec code in ns
makecommand(app, name, python)
if __name__ == '__main__':
app = Tkinter.Tk()
setup_send(app, {})
app.mainloop()
#
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Re: Running Python Scripts With 'sudo'
Does "sudo" sanitize the environment? Imagine that the user can set PYTHONPATH, PYTHONINSPECT, etc. Beyond that, you have the same problems as with any code that runs with "extra privileges". Can the user supply any code that is fed to patently unsafe primitives (like the unpickler, eval() or the exec statement)? If your program opens files with user-controlled names, did you make all the right checks? Jeff pgpLhnjBDThEJ.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: tkinter absorb chars
On Wed, Mar 02, 2005 at 04:58:03PM -0600, phil wrote:
> Sorry for the repost, but moderator
> jeld the last one,
We saw both posts.
> In a Tkinter entry field (or Pmw entry)
> how could I eat charactres?
create a binding on the widget for the particular character you want to
treat specially. If you want to suppress that character, return the
string "break" from the binding. Example:
from Tkinter import *
t = Tkinter.Tk()
e = Tkinter.Entry(t); e.pack()
e.bind("x", lambda event: "break")
Jeff
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Re: Tough Spawn Problem
By using os.spawn* and the os.P_NOWAIT, the spawn function will return immediately, with the return value being the PID of the new process. Later, you can use os.kill() to force the program to terminate, os.waitpid() to retrieve the exit status if it has terminated, or you could use the signal module to wait for SIGCHLD to be delivered at the time the child terminates. With os.spawn*, the child's open files (including stdin and stdout) are the same as the parent's; using the popen2 module, you can send the program input and capture its output too. Here's the program I ran on Linux (Fedora Core 2 / Python 2.3) to show that os.P_NOWAIT works fine: import os pid = os.spawnv(os.P_NOWAIT, "/bin/sh", ["sh", "-c", "sleep 1; echo spawned program"]) print "child is pid", pid print "waitpid result is", os.waitpid(pid, 0) and the output is $ python /tmp/googlemike.py child is pid 13874 spawned program waitpid result is (13874, 0) the fact that "spawned program" is printed after "child is pid N" shows that the python program continues executing while the child is working (or, in this case, sleeping). Jeff pgp8mSLDOEMJm.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: reversed heapification?
Can you use something like (untested) class ComparisonReverser: def __init__(self, s): self.s = s def __cmp__(self, o): return cmp(o, self.s) def __lt__... # or whichever operation hashes use then use (ComparisonReverser(f(x)), i, x) as the decorated item instead of (f(x), i, x) Jeff pgpKui90u477G.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: pyconfig.h
The pyconfig.h file (/usr/include/python2.3/pyconfig.h) should begin something like this /* pyconfig.h. Generated by configure. */ /* pyconfig.h.in. Generated from configure.in by autoheader. */ and shouldn't cause problems. If it starts in a wildly different way than that, then it's probably due to something unique SUSE did in packaging Python. If you're having problems with SUSE's own modifications, then the place to go is probably their bug database or mailing lists. Jeff pgp3KIk3XPCY9.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Unicode BOM marks
On Mon, Mar 07, 2005 at 11:56:57PM +0100, Francis Girard wrote:
> BTW, the python "unicode" built-in function documentation says it returns a
> "unicode" string which scarcely means something. What is the python
> "internal" unicode encoding ?
The language reference says farily little about unicode objects. Here's
what it does say: [http://docs.python.org/ref/types.html#l2h-48]
Unicode
The items of a Unicode object are Unicode code units. A Unicode
code unit is represented by a Unicode object of one item and can
hold either a 16-bit or 32-bit value representing a Unicode
ordinal (the maximum value for the ordinal is given in
sys.maxunicode, and depends on how Python is configured at
compile time). Surrogate pairs may be present in the Unicode
object, and will be reported as two separate items. The built-in
functions unichr() and ord() convert between code units and
nonnegative integers representing the Unicode ordinals as
defined in the Unicode Standard 3.0. Conversion from and to
other encodings are possible through the Unicode method encode
and the built-in function unicode().
In terms of the CPython implementation, the PyUnicodeObject is laid out
as follows:
typedef struct {
PyObject_HEAD
int length; /* Length of raw Unicode data in buffer */
Py_UNICODE *str;/* Raw Unicode buffer */
long hash; /* Hash value; -1 if not set */
PyObject *defenc; /* (Default) Encoded version as Python
string, or NULL; this is used for
implementing the buffer protocol */
} PyUnicodeObject;
Py_UNICODE is some "C" integral type that can hold values up to
sys.maxunicode (probably one of unsigned short, unsigned int, unsigned
long, wchar_t).
Jeff
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Re: pymem.h In function '__declspec'
What does this command print? gcc -c -I/usr/Python-2.3.3/Include -x c -o /dev/null \ /usr/Python-2.3.3/Include/pymem.h If it prints an error like the one you included in this message, then the set of header files in /usr/Python-2.3.3/Include is damaged, incomplete, or wrong for your compiler environment. If the files in /usr/Python-2.3.3 are from SUSE, then contact your vendor. If it doesn't give an error, but the build of your "application RPM" does, then investigate the compiler defines that are present in the application that aren't on the above commandline. For instance, I was able to get errors like yours by using inappropriate compiler options: $ gcc -DPy_ENABLE_SHARED -DHAVE_DECLSPEC_DLL -c -x c -o /dev/null \ /usr/include/python2.3/Python.h In file included from /usr/include/python2.3/Python.h:67: /usr/include/python2.3/pymem.h: In function `__declspec': /usr/include/python2.3/pymem.h:51: error: syntax error before "__declspec" You're right that __declspec has something to do with Windows DLLs. Normally, Python uses the macro 'PyAPI_FUNC' to declare all functions in its header files. For certain compilers (msvc, cygwin, mingw) it's appropriate to use the __declspec extension to make the Python shared library work properly. For other compilers, PyAPI_FUNC doesn't do anything special. It's through the presence of absence of defines like Py_ENABLE_SHARED and HAVE_DECLSPEC_DLL that Python decides how to define PyAPI_FUNC, and this little detail is usually below the radar. Jeff pgppEf9f5kh5m.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: problem with "time"
Without your code, it's hard to tell. Here's a small program I wrote: import time t = time.time() print time.localtime(t - 86400) print time.localtime(t) on both lines, the tm_isdst flag is the same. If I choose two times that are on either side of the DST change in my timezone, I get different answers: import time t = time.time() print time.localtime(t) print time.localtime(t+86400 * 90) Here, I get different values for tm_isdst because DST is in effect for one of the times but not the other. > I have _no_ idea on how localtime() could reasonably synthesize > different values for that flag for _any_ time value converted in about > the same millisecond. What gives? The tm_isdst field is not about the DSTness at the time of conversion---it's about the DSTness of the converted time. Jeff pgpNFKAG8aJuW.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Is there a short-circuiting dictionary "get" method?
untested def my_getter(m, i, f): try: return m[i] except (KeyError, IndexError): return f() my_getter(d, 'x', bigscaryfunction) my_getter(d, 'y', lambda: scaryinlineexpresion) pgp04VRKFqQL1.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Apparently, I don't understand threading
Ah -- I'm sorry I was off-target, and I'm glad someone else had what may be better advice for you. Jeff pgptOZnkOhiE1.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Accessing the contents of a 'cell' object from Python
Here's an old thread I contributed to which had a similar function (called 'cell_get' in this case) http://groups-beta.google.com/group/comp.lang.python/browse_thread/thread/baba3b943524a92c/71b57a32b311ffc8?q=func_closure#71b57a32b311ffc8 http://groups-beta.google.com/group/comp.lang.python/msg/71b57a32b311ffc8?dmode=source Jeff pgpXLMoKMtyfX.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Pre-PEP: Dictionary accumulator methods
Maybe something for sets like 'appendlist' ('unionset'?)
Jeff
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Re: Pre-PEP: Dictionary accumulator methods
> [Jeff Epler]
> > Maybe something for sets like 'appendlist' ('unionset'?)
>
On Sat, Mar 19, 2005 at 04:18:43AM +, Raymond Hettinger wrote:
> I do not follow. Can you provide a pure python equivalent?
Here's what I had in mind:
$ python /tmp/unionset.py
Set(['set', 'self', 'since', 's', 'sys', 'source', 'S', 'Set', 'sets',
'starting'])
#
try:
set
except:
from sets import Set as set
def unionset(self, key, *values):
try:
self[key].update(values)
except KeyError:
self[key] = set(values)
if __name__ == '__main__':
import sys, re
index = {}
# We need a source of words. This file will do.
corpus = open(sys.argv[0]).read()
words = re.findall('\w+', corpus)
# Create an index of the words according to the first letter.
# repeated words are listed once since the values are sets
for word in words:
unionset(index, word[0].lower(), word)
# Display the words starting with 'S'
print index['s']
#
Jeff
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Re: subprocess 'wait' method causes .py program to hang.
You can use PROC.poll() to find out whether the process has exited yet or not (for instance, in a 'while' loop along with a delay). I don't know what facilities exist to forcibly terminate programs on Windows, though. On Unix, os.kill() can be used to kill a process given its pid. Perhaps some of the functions in the 'win32process' module of win32all can help. Here's an example for Windows written in C: http://win32.mvps.org/processes/fkill.html Jeff pgpZEr2XdFCHl.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: List limits
I'm referring to Python 2.2's C headers as I answer this question. I believe some of may have changed by 2.4. The number of elements in a "variable-sized object" (those with Py_VAR_HEAD; I believe this includes lists, tuples, and strings) is stored in a platform 'int'. On most (desktop) systems, this means the limit of any sized object is no more than 2**31-1, or about 2 billion. On those same systems, a list object of length 128 million, give or take, approximately 512 megabytes of memory will be allocated for the list object itself (4 bytes for each pointer-to-element). If each element of the list is distinct, those objects will each require additional memory---The smallest useful Python object takes around 16 bytes, IIRC, which would bring the total memory required to around 2560 megabytes if I didn't screw up my arithmetic. This is close to (or over, depending on the system) the maximum amount of physical RAM these machines can accomodate, and the maximum amount of address space available to a single program. While performing list-resizing operations, there may be a temporary need for two copies of the list object itself, bumping the memory used up to 3 gigs. Finally, the speed of some operations (l.index(item), l.pop(0), l.insert(0, item)) are related linearly to the size of the list, so your program may slow down as the lists it manipulates grow. Others, such as l[i], l.pop(), and l.append(item), are constant-time or amortized-constant- time. Jeff pgpan9zxo4Sv8.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Processes and their childs
"flush" your files before forking.
For me, this program gives the correct output 'hello\n' when correct=1.
When correct=0, I get either 'hello\nhello' or 'hellohello\n' as output.
correct = 0
import sys, os
sys.stdout.write('hello')
if correct: sys.stdout.flush()
if os.fork() == 0: sys.stdout.write('\n')
Jeff
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Re: character set gobbledy-gook ascii translation ...
>>> email.Header.decode_header("=?us-ascii?Q?Re=3A=20=5Bosg=2Duser=5D=20Culling=20problem?=")
[('Re: [osg-user] Culling problem', 'us-ascii')]
>>> email.Header.decode_header("=?gb2312?B?cXVlc3Rpb24gYWJvdXQgbG9hZGluZyBmbHQgbGFyZ2UgdGVycmFpbiA=?=")
[('question about loading flt large terrain ', 'gb2312')]
>>> help(email.Header.decode_header)
Help on function decode_header:
decode_header(header)
Decode a message header value without converting charset.
Returns a list of (decoded_string, charset) pairs containing each of
the decoded parts of the header. Charset is None for non-encoded
parts of the header, otherwise a lower-case string containing the
name of the character set specified in the encoded string.
An email.Errors.HeaderParseError may be raised when certain decoding
error occurs (e.g. a base64 decoding exception).
Jeff
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Re: Clearing the screen
I don't know about idle, but the "real" python supports the PYTHONSTARTUP environment variable. PYTHONSTARTUP If this is the name of a readable file, the Python commands in that file are executed before the first prompt is displayed in interactive mode. The file is executed in the same name space where interactive commands are executed so that objects defined or imported in it can be used without qualification in the interactive session. You can also change the prompts sys.ps1 and sys.ps2 in this file. Jeff pgpqil4r6wyiw.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Execute code after death of all child processes - (corrected posting)
First, you'll want to exit from each forked copy, or else it will reach the code-after-the-for-loop: import sys, os, time texts = ['this is text1', 'this is text 2'] for current_text in texts[0:]: pid = os.fork() if pid == 0: time.sleep(2) print current_text raise SystemExit Next, you'll want to wait for each process you started: for current_text in texts: os.waitpid(-1, 0) print 'this is the end' $ python /tmp/franz.py this is text1 this is text 2 this is the end Jeff pgp37vjgFm0zM.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: copying classes?
You copied an instance, not a class. Here's an example of attempting to deepcopy a class: >>> class X: pass ... >>> import copy >>> X is copy.deepcopy(X) Traceback (most recent call last): File "", line 1, in ? File "/usr/lib/python2.2/copy.py", line 179, in deepcopy raise error, \ copy.Error: un-deep-copyable object of type In theory, one could provide a metaclass that allows copying of instances of that metaclass. I'll leave this as an exercise to the reader. Jeff pgpjJrXN93ruF.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: how can I put a 1Gb file in a zipfile??
The limits of ZIP files according to the folks who make info-zip:
http://www.info-zip.org/pub/infozip/FAQ.html#limits
statistic limit
number of files65,536
uncompressed size of a single file 4 GB
compressed size of a single file 4 GB
total size of archive 256 TB
maximum path/filename length64 KB
I had no trouble creating a zip file from a 4GB file filled with '\0'
bytes:
$ python bennie.py
$ ls -ls test.zip big
12 -rw-rw-r-- 1 jepler jepler 4294967296 Mar 20 14:11 big
4084 -rw-rw-r-- 1 jepler jepler4174545 Mar 20 14:14 test.zip
I'm using Python 2.3.3 on Fedora Core 2.
#
# bennie.py
def make_4gb_file(f):
f = open(f, "w")
f.seek ( 4 * 1024 * 1024 * 1024 - 1)
f.write("\0")
f.close()
import zipfile
z = zipfile.ZipFile("/tmp/test.zip", "w", zipfile.ZIP_DEFLATED)
make_4gb_file("/tmp/big")
z.write("/tmp/big")
z.close()
#
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Re: Shell re-direction
buffering. In the first case, there is either no buffering, or line buffering on sys.stdout, so you see the lines in order. In the second case, there is a buffer of a few hundred or thousand bytes for stdout in the python process, and you see the two lines of python output together (in this case, when the python process exits and flushes all its buffers). You can use the "flush" method on file objects to "clear out" these buffers. Jeff pgpJceNYE0Rop.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: spaces in re.compile()
Maybe you want r'\b'. From 'pydoc sre':
\b Matches the empty string, but only at the start or end of a word.
import re
r = re.compile( r'\btest\b' )
print r.findall("testy")
print r.findall(" testy ")
print r.findall(" test ")
print r.findall("test")
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Re: possible bug?
On Tue, Mar 22, 2005 at 07:16:11AM -0700, Earl Eiland wrote: > I've been having trouble with a program hanging when using the > subprocess modules "wait()" method. Replacing it with with a loop that > used "poll()" solved the problem. Please include an example, and more information about what platforn you're using This simple program worked fine for me on Linux with Python 2.4: # import subprocess, time s = subprocess.Popen(['sleep', '2']) while 1: time.sleep(.1) if s.poll() is not None: break print "polling wait done", s.returncode s = subprocess.Popen(['sleep', '2']) s.wait() print "blocking wait done", s.returncode # Jeff pgpq6ATZLp4Bp.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: possible bug?
I wrote a program to use subprocess.Popen 1 times, and never had
.wait() hang. If this is a bug, it may be Windows specific.
Here's the program I ran:
#-
import subprocess, signal
def timeout(*args):
print "Timed out waiting on", i
raise SystemExit, 1
signal.signal(signal.SIGALRM, timeout)
for i in xrange(1):
signal.alarm(5)
subprocess.Popen(['/bin/true']).wait()
if i % 100 == 0: print "done with", i
print "done!"
#-
If the wait method ever hangs, the signal handler shuld be invoked. On
Unix, "/bin/true" is a very simple program that does nothing, so it's
virtually guaranteed to run in less than 5 seconds. On Windows, maybe
you want something like subprocess.popen('cmd.exe /c rem') as a command
that will do nothing and terminate quickly. What happens if you run my
program with that change to the Popen line?
Jeff
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Re: possible bug?
hm, I guess SIGALRM doesn't exist on Windows. You can run the program without the 'signal.signal' line or the 'signal.alarm' line, and you'll be stuck with a hung Python if subprocess.Popen exhibits the bug. Jeff pgp80TDX5i7qo.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: possible bug?
On Tue, Mar 22, 2005 at 02:19:52PM -0700, Earl Eiland wrote: > Well, your program ran successfully. Perhaps WinRK is not well > behaved. How can a process terminate in such a way that poll() can read > it, but wait() won't? I don't have any idea. Both are implemented in terms of win32event.WaitForSingleObject (which is itself a thin wrapper over the win32 API of the same name[1]), one with a zero timeout and one with an INFINITE timeout. This caveat is in the msdn page on WFSO: Use caution when calling the wait functions and code that directly or indirectly creates windows. If a thread creates any windows, it must process messages. Message broadcasts are sent to all windows in the system. A thread that uses a wait function with no time-out interval may cause the system to become deadlocked. Two examples of code that indirectly creates windows are DDE and the CoInitialize function. Therefore, if you have a thread that creates windows, use MsgWaitForMultipleObjects or MsgWaitForMultipleObjectsEx, rather than WaitForSingleObject. ... which is pretty much greek to this unix geek. If your Python program has a GUI, can you strip out the gui-related parts to make it a pure commandline program, and see if you still have the problem? You could try something like (untested, obviously) import subprocess if subprocess.mswindows: from win32event import WaitForSingleObject from win32process import GetExitCodeProcess def wait(self): """Wait for child process to terminate. Returns returncode attribute.""" while self.returncode is None: obj = WaitForSingleObject(self._handle, 1000) self.returncode = GetExitCodeProcess(self._handle) _active.remove(self) return self.returncode subprocess.Popen.wait = wait to make the .wait() method call WFSO with a timeout, and then maybe you can simply forget about the weird behavior you ran into. Jeff [1] http://msdn.microsoft.com/library/en-us/dllproc/base/waitforsingleobject.asp pgpDmLreIsHC0.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Python RegExp
On my machine the program finishes in 30 seconds. (it's a 1.5GHz machine) If the 'parm' group is removed, or if the buffer is shortened, the time is reduced considerably. There are "pathological cases" for regular expressions which can take quite a long time. In the case of your expression, it's happening for the group 'parm'. I think, but don't know, that each time a candidate for 'parm' is found, the following '#' (or maybe the second '<'?) is not found, and it backtracks to try to match 'parm' in a different way, which involves considering many different combinations (basically, each 'name=' could be the start of a new instance of the first parenthsized subgroup of , or it could be part of the character class that includes [a-zA-Z=]) You may wish to consider using other approaches for parsing this text than regular expressions. Jeff pgpKO1Ax9UfsJ.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: How to get TabError?
When running with "-tt", you can get this error. [EMAIL PROTECTED] src]$ python -tt Python 2.3.3 (#1, May 7 2004, 10:31:40) [GCC 3.3.3 20040412 (Red Hat Linux 3.3.3-7)] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> exec "def f():\n\ta\nb" Traceback (most recent call last): File "", line 1, in ? File "", line 3 b ^ TabError: inconsistent use of tabs and spaces in indentation pgpMSKzPbMB1C.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: [Tkinter] LONG POST ALERT: Setting application icon on Linux
Here is a short program that sets Tk's window icon on Linux. My window
manager is icewm, and it uses a scaled version of the "flagup" image
both at the upper-left corner of the window and on the task bar entry
for the window.
import Tkinter
app = Tkinter.Tk()
app.iconbitmap("@/usr/X11R6/include/X11/bitmaps/flagup")
app.mainloop()
As often happens, the Tkinter documentation doesn't tell the whole
story---you have to dig into the Tk documentation. I started with "man
n wm", and read the following:
If bitmap is specified, then it names a bitmap in the standard
forms accepted by Tk (see the Tk_GetBitmap manual entry for
details).
OK, on to Tk_GetBitmap...
@fileName FileName must be the name of a file containing a
bitmap description in the standard X11 or X10 format.
and I happened to know that some bitmaps in this format exist in the
directory I mentioned above. Note that the "standard X11 format" is
monochrome, so you will not be able to use color images with
"iconbitmap" on Linux. Tk doesn't support _NET_WM_ICON for setting
full-color icons.
Jeff
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Re: [Tkinter] LONG POST ALERT: Setting application icon on Linux
I have written a rather hackish extension to use NET_WM_ICON to set full-color icons in Tkinter apps. You can read about it here: http://craie.unpy.net/aether/index.cgi/software/01112237744 you'll probably need to take a look at the EWMH spec, too. If KDE supports NET_WM_ICON, this may work for you (but you'll have to convert your image manually to the format required for NET_WM_ICON) Best of luck! Unfortunately, the code is not supported. Jeff pgpfvrqv1Xqtz.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Our Luxurious, Rubinesque, Python 2.4
In my experience, when built with the same compiler (gcc 3.3.3) the size of the python library file (libpython2.x.a on unix machines) hasn't changed much between 2.3, 2.4, and current CVS: -rw-r--r-- 1 jepler jepler 950426 Mar 31 21:37 libpython2.3.a -rw-rw-r-- 1 jepler jepler 1002158 Mar 31 21:36 libpython2.4.a -rw-rw-r-- 1 jepler jepler 1001982 Mar 31 21:36 libpython2.5.a Between Python 2.3 and 2.4, the python.org people switched to a different version of the Microsoft C compiler. Perhaps this is (part of) the explanation. Jeff pgp0gJIvdwEj2.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Spider - path conflict [../test.htm,www.nic.nl/index.html]
I think you want urllib.basejoin().
>>> urllib.basejoin("http://www.example.com/test/page.html";, "otherpage.html")
'http://www.example.com/test/otherpage.html'
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Re: Corectly convert from %PATH%=c:\\X; "c:\\a; b" TO ['c:\\X', 'c:\\a; b']
if your goal is to search for files on a windows-style path environment variable, maybe you don't want to take this approach, but instead wrap and use the _wsearchenv or _searchenv C library functions http://msdn.microsoft.com/library/en-us/vclib/html/_crt__searchenv.2c_._wsearchenv.asp Incidentally, I peeked at the implementation of _searchenv in wine (an implementation of the win32 API for Unix), and it doesn't do the quote-processing that you say Windows does. The msdn page doesn't give the syntax for the variable either, which is pretty typical. Do you have an "official" page that discusses the syntax? Jeff pgpT4weDOp5pO.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: "specialdict" module
The software you used to post this message wrapped some of the lines of code. For example: > def __delitem__(self, key): > super(keytransformdict, self).__delitem__(self, > self._transformer(key)) In defaultdict, I wonder whether everything should be viewed as a factory: def setdefaultvalue(self, value): def factory(): return value self.setdefaultfactory(factory) and the "no-default" mode would either cease to exist, or def cleardefault(self): def factory(): raise KeyError, "key does not exist and no default defined" self.setdefaultfactory(factory) (too bad that the key isn't available in the factory, this degrades the quality of the error messge) if so, __getitem__ becomes simpler: __slots__ = ['_default'] def __getitem__(self, key): try: return super(defaultdict, self).__getitem__(key) except KeyError: return self.setdefault(key, apply(*self._default)) I don't ever have an itch for sorted dictionaries, as far as I can remember, and I don't immediately understand the use of keytransformdict. Can you give an example of it? Jeff pgpTcdOKCij9W.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Corectly convert from %PATH%=c:\\X; "c:\\a; b" TO ['c:\\X', 'c:\\a; b']
The C code that Python uses to find the initial value of sys.path based
on PYTHONPATH seems to be simple splitting on the equivalent of
os.pathsep. See the source file Python/sysmodule.c, function
makepathobject().
for (i = 0; ; i++) {
p = strchr(path, delim); // ";" on windows, ":" on unix
if (p == NULL) ...
w = PyString_FromStringAndSize(path, (int) (p - path));
if (w == NULL) ...
PyList_SetItem(v, i, w);
if (*p == '\0')
break;
path = p+1;
}
No special handling of quote characters happens here.
> I think I will stick to a simple splitting at the ;. Luckily all the
> directories I am dealing with have nice names.
If you do this, you'll match the behavior of python itself, and you'll match
the behavior of wine.
> I have not even tried to see what quirks there exist with unix.
None. There's no way to quote anything in paths, so while you can't place a
directory with a colon in its name on your path, nobody loses any sleep over
it either. Here's what the Open Group has to say about PATH:
PATH
This variable shall represent the sequence of path prefixes that
certain functions and utilities apply in searching for an executable
file known only by a filename. The prefixes shall be separated by a
colon ( ':' ). When a non-zero-length prefix is applied to this
filename, a slash shall be inserted between the prefix and the
filename. A zero-length prefix is a legacy feature that indicates the
current working directory. It appears as two adjacent colons ( "::" ),
as an initial colon preceding the rest of the list, or as a trailing
colon following the rest of the list. A strictly conforming application
shall use an actual pathname (such as .) to represent the current
working directory in PATH . The list shall be searched from beginning
to end, applying the filename to each prefix, until an executable file
with the specified name and appropriate execution permissions is found.
If the pathname being sought contains a slash, the search through the
path prefixes shall not be performed. If the pathname begins with a
slash, the specified path is resolved (see Pathname Resolution). If
PATH is unset or is set to null, the path search is
implementation-defined.
ah, if only windows was so well-defined!
Jeff
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Re: Silly question re: 'for i in sys.stdin'?
The iterator for files is a little bit like this generator function: def lines(f): while 1: chunk = f.readlines(sizehint) for line in chunk: yield line Inside file.readlines, the read from the tty will block until sizehint bytes have been read or EOF is seen. If you want this kind of line-at-a-time functionality, then you could use the iter(callable, sentinel) form, and switch between it and the readlines method based on a commandline flag or whether the file satisfies 'os.isatty()': def lines(f): # untested """lines(f) If f is a terminal, then return an iterator that gives a value after each line is entered. Otherwise, return the efficient iterator for files.""" if hasattr(f, "fileno") and isatty(f.fileno()): return iter(f.readline, '') return iter(f) for line in lines(sys.stdin): doSomethingWith(line) Jeff pgpisrc7TrsDv.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Silly question re: 'for i in sys.stdin'?
On Sun, Apr 03, 2005 at 09:49:42PM -0600, Steven Bethard wrote: > Slick. Thanks! does isatty() actually work on windows? I'm a tiny bit surprised! Jeff pgp2TeZpqhdyV.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Re: Tkinter - pixel or widget color
On Mon, Apr 04, 2005 at 10:43:11AM +0200, pavel.kosina wrote: > I would need to get at canvas pixel color under certain moving widget or > better (= faster?) colors/"types" of underlying static widgets that are > of polygon shape (not rectangle). I don't believe this information is available anywhere, unfortunately. Jeff pgpJe2gd1ST4h.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
