Re: Customizing class attribute access in classic classes
On Oct 30, 4:16 am, Ben Finney wrote: > Geoff Bache writes: > > I'm wondering if there is any way to customize class attribute access > > on classic classes? > > Why do that? What is it you're hoping to achieve, and why limit it to > classic classes only? > I'm building a mocking tool, CaptureMock, which works by intercepting and capturing particular calls, recording and replaying them. A user can just say "intercept httplib for me" and it will record all the interactions with httplib and allow a test that can be run without doing anything via http or writing any handcrafted "mock-code". So I need to be able to intercept also static attribute access, say httplib.HTTPConnection.request. httplib.HTTPConnection is a classic class. I can make my intercepting version of it into a new-style class but the risk is that that will change its behaviour in subtle ways, negating the point of the tool. As for limiting it to classic classes only, I obviously need to do it on new-style classes also. But I know how to do that... Regards, Geoff Bache -- http://mail.python.org/mailman/listinfo/python-list
Re: Customizing class attribute access in classic classes
On Sat, 29 Oct 2011 14:06:12 -0700, Geoff Bache wrote: > Hi, > > I'm wondering if there is any way to customize class attribute access on > classic classes? > > So this works: > > class Meta(type): > def __getattr__(cls, name): > return "Customized " + name > > class A: > __metaclass__ = Meta > > print A.blah > > but it turns A into a new-style class. And why is this a problem? In any case, metaclasses work for classic classes. Metaclasses go back to pre-Python 1.5, long before new-style classes and type unification. http://www.python.org/doc/essays/metaclasses/ You just have to do a lot more work: class Meta: def __init__(self, name, bases, namespace): self.__name__ = name self.__bases__ = bases self.__dict__ = namespace def __str__(self): return "" __repr__ = __str__ def __getattr__(self, name): return "Customized " + name def __call__(self): return self (The purpose of the __str__ and __repr__ methods is to make it possible to experiment in the interactive interpreter, without a lot of mysterious and puzzling "str object is not callable" TypeErrors. Trust me on this.) And in use: >>> class Spam: ... __metaclass__ = Meta ... a = 1 ... >>> Spam.b 'Customized b' But note that using classic classes, there is no equivalent of __getattribute__ or descriptors, so there is no way to customize access of an attribute which actually does exist: >>> Spam.a 1 -- Steven -- http://mail.python.org/mailman/listinfo/python-list
Re: Customizing class attribute access in classic classes
Thanks for this Steven. I'm however gettings some pretty odd effects, both on method access and inheritance. I expanded your example a bit... class Meta: def __init__(self, name, bases, namespace): self.__name__ = name self.__bases__ = bases self.__dict__ = namespace def __str__(self): return "" __repr__ = __str__ def __getattr__(self, name): return "Customized " + name def __call__(self): return self class Base: def basemethod(self): return "base" class A(Base): __metaclass__ = Meta def method(self): return "answer" The effect seems to be to make all methods of A into static methods, and to ignore its base classes altogether: >>> a = A() >>> print a.blah2 Customized blah2 >>> print a.method() Traceback (most recent call last): File "", line 1, in TypeError: method() takes exactly 1 argument (0 given) >>> print a.method(1) answer >>> print A.method(1) answer >>> print a.basemethod() Traceback (most recent call last): File "", line 1, in TypeError: 'str' object is not callable >>> isinstance(a, Base) False Regards, Geoff Bache -- http://mail.python.org/mailman/listinfo/python-list
Re: Need Windows user / developer to help with Pynguin
On 30/10/2011 1:43 AM, Lee Harr wrote: For Windows users who want to just run Pyguin (not modify or tinker with the source code), it would be best to bundle Pynguin up with Py2exe I considered that, but I agree that licensing issues would make it problematic. What licensing issues concern you? The py2exe license shouldn't be a problem and py2exe or something like it is good advice. Mark -- http://mail.python.org/mailman/listinfo/python-list
Re: Dynamically creating properties?
To be honest, I was hoping someone would have posted a link to a well known and tested recipe. You'd think this function would be in the standard library or a specific Exception tied directly with setattr() and getattr() (and possibly __getattr__(), __getattribute__(), __setattr__()) The main thing I wanted to point out though is when you start using dynamically named references, there's more to it then just letting a dynamic file define it. If there's a way to reference a set of data, it really shouldn't be with a "dynamically named reference" too often. Databases are a good example. Perhaps this is a better way for example: If you have a bunch of tables in your DB -is- it better to get the table def and create a Python class with dynamically named "fields"? Or is it better to create a Table class with name attribute and a Field class with a name attribute (named "name") SO instead of : field_name = xml_parse.get_next_field_name(xml_table_definition) my_table = Table() setattr(my_table, field_name, empty_list_to_later_contain_field_data) Perhaps: field_name = xml_parse.get_next_field_name(xml_table_definition) my_table = Table() my_table.fields[field_name] = empty_list_to_later_contain_field_data # or my_table.add_field( Field(field_name) ) -- http://mail.python.org/mailman/listinfo/python-list
[Help] python ctypes to process C pointer!
A c code snippet,the c file compiled to a dll file named libxxx.dll:
typedef void* HND;
typedef unsigned char UCHAR;
typedef short int SWORD;
...
int Connect(
HND* hnd,
UCHAR* ipaddr,
SWORD port){
..
return 1;
}
then How to handle function Connect using python and ctypes. especially the
parameter hnd?
My python code:
from ctypes import *
xxx = cdll.libxxx
xxx.Connect.restype=c_int
xxx.Connect.argstype=[c_wchar_p,c_wchar_p,c_int]
hnd=c_char_p()
buf=create_string_buffer("127.0.0.1\0")
ipaddr=cast(buf,POINTER(c_char))
xxx.Connect(byref(hnd),ipaddr,8000)
But I always result a error:
WindowsError: exception: access violation writing 0x
How to fix this problem?
Thanks.
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__init__ with multiple list values
Initializing a list of objects with one value: class Order: def __init__(self, ratio): self.ratio=ratio def __call__(self): return self.ratio ratio=[1, 2, 3, 4, 5] Orders=[Order(x) for x in ratio] But now I want to __init__ with 3 values: class Order: def __init__(self, ratio, bias, locus): self.ratio=ratio self.bias=bias self.locus=locus def __call__(self): return self.ratio, self.bias, self.locus ratio=[1, 2, 3, 4, 5] bias=[True, False, True, False, True] locus=['A', 'B', 'C', 'D', 'E'] Orders=[Order(x,y,z) for x,y,z in [ratio, bias, locus]] >>> ValueError: too many values to unpack (expected 3) How to do it? -- Gnarlie -- http://mail.python.org/mailman/listinfo/python-list
Re: Review Python site with useful code snippets
Considering that the site is going to grow over time, putting the snippets in a drop-down menu isn't a wise idea in my opinion. Snippets on a separate page like activestate python would make it more convenient. Nice initiative, and would be very helpful when it grows over time. -- http://mail.python.org/mailman/listinfo/python-list
Re: __init__ with multiple list values
On Mon, Oct 31, 2011 at 2:02 AM, Gnarlodious wrote: > Orders=[Order(x,y,z) for x,y,z in [ratio, bias, locus]] > Assuming that you intend to take the first element of each list, then the second, and so on, you'll want to use zip(): Orders=[Order(x,y,z) for x,y,z in zip(ratio, bias, locus)] With your syntax, Python iterates over a three-element list. The first iteration, it looks at 'ratio' and tries to unpack that into x,y,z; this doesn't work, because ratio has five elements. The second iteration would try to unpack 'bias', and the third would go for 'locus'. The zip function returns tuples of (ratio[N], bias[N], locus[N]) for successive Ns: >>> list(zip(ratio,bias,locus)) [(1, True, 'A'), (2, False, 'B'), (3, True, 'C'), (4, False, 'D'), (5, True, 'E')] ChrisA -- http://mail.python.org/mailman/listinfo/python-list
[ANN] Pyrolite 1.3 - native Pyro and Pickle library for Java and .NET
Hello, I'd like to announce Pyrolite 1.3, a tiny (~50k) Pyro client library for Java and .NET. Q: "what is a java/.net library doing in this newsgroup?" A.1: This library is meant to connect a Java or .NET program to Python in a very simple way, using the Pyro protocol. Pyro is my remote object library or Python. A.2: Pyrolite contains an almost feature complete native implementation of Python's pickle protocol. This can be useful by itself to read/write pickles from Java or .NET programs. Download Pyrolite here: http://irmen.home.xs4all.nl/pyrolite/ More info on Pyrolite: http://irmen.home.xs4all.nl/pyrolite/README.txt More info on Pyro: http://irmen.home.xs4all.nl/pyro/ Enjoy, Irmen de Jong -- http://mail.python.org/mailman/listinfo/python-list
Re: __init__ with multiple list values
On Oct 30, 9:15 am, Chris Angelico wrote: > Orders=[Order(x,y,z) for x,y,z in zip(ratio, bias, locus)] Brilliant, thanks! -- Gnarlie -- http://mail.python.org/mailman/listinfo/python-list
RE: Need Windows user / developer to help with Pynguin
>>> Py2exe >> >> I considered that, but I agree that licensing issues would make it >> problematic. > > What licensing issues concern you? The py2exe license shouldn't be a > problem and py2exe or something like it is good advice. I think PyQt 4 would be the biggest issue. It is GPL 2 / 3. I think if this were just for my own use, or just for use in getting the program on to computers in my own school's labs then py2exe would be fine. I don't think I could post a py2exe'd version on the google code site for general distribution. Of course this is only my own personal (non-legal) opinion. -- http://mail.python.org/mailman/listinfo/python-list
Re: Need Windows user / developer to help with Pynguin
Maybe push something onto pip or easy_install? On Fri, Oct 28, 2011 at 6:38 AM, Lee Harr wrote: > > I develop the free python-based turtle graphics application pynguin. > > http://pynguin.googlecode.com/ > > > Lately I have been getting a lot of positive comments from people > who use the program, but I am also getting a lot of feedback from > people on Windows (mostly beginners) who are having trouble > getting the program running. > > I don't use Windows myself, though I have found access occasionally > to fix bugs. I just don't know enough about Windows culture to be > able to make a reliable method for installing or running the program. > > > The method that I wrote for Linux also works on Windows, but it has > to be run from the command prompt. > > > I am hoping someone can look at what is there and come up with a > reliable method or a simple set of steps that people can follow to get > up and running. Hopefully without having to resort to the command > prompt. > > I started a wiki page here: > http://code.google.com/p/pynguin/wiki/InstallingPynguinOnWindows > but I can't even test if it actually works > > > Thanks for any help. > > > -- > http://mail.python.org/mailman/listinfo/python-list > -- http://mail.python.org/mailman/listinfo/python-list
Re: __init__ with multiple list values
On 30/10/2011 15:02, Gnarlodious wrote: Initializing a list of objects with one value: class Order: def __init__(self, ratio): self.ratio=ratio def __call__(self): return self.ratio ratio=[1, 2, 3, 4, 5] Orders=[Order(x) for x in ratio] But now I want to __init__ with 3 values: class Order: def __init__(self, ratio, bias, locus): self.ratio=ratio self.bias=bias self.locus=locus def __call__(self): return self.ratio, self.bias, self.locus ratio=[1, 2, 3, 4, 5] bias=[True, False, True, False, True] locus=['A', 'B', 'C', 'D', 'E'] Orders=[Order(x,y,z) for x,y,z in [ratio, bias, locus]] ValueError: too many values to unpack (expected 3) How to do it? Use 'zip': Orders=[Order(x,y,z) for x,y,z in zip(ratio, bias, locus)] -- http://mail.python.org/mailman/listinfo/python-list
Calling JavaScript inside the webbrowser module
Hi!
Is there anyway to communicate with JavaScript inside a website opened via the
webbrowser module?
| import webbrowser
| webbrowser.open('http://python.org')
Here I'd like to do something like webbrowser.call('alert(1)')
and I'd like to be able to call the python app from javascript too.
I've looked at pywebkitgtk, but it's messy running on win32.
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Appending to sys.path during module install with distutils
I'm trying to use distutils to install a collection of modules in /usr/local/lib/python2.7/site-packages. My distribution (Fedora 15) doesn't include any /usr/local paths in sys.path, so the import fails when running the program. The distutils documentation suggests adding a $NAME.pth file to an existing site-packages directory in sys.path. Is there a preferred/accepted method of doing this? I considered just adding some code to my setup.py to generate a braindump.pth file containing something like: PREFIX/lib/pythonMAJOR.MINOR/site-packages and then walking the existing sys.path and picking one of those site-packages directories to install braindump.pth to. I'm not sure how to determine which is the appropriate path. Maybe I'm going about this completely wrong as well - anyone care to help steer me in the right direction? The project is located here: http://braindump.dvhart.com in case anyone wants it for reference. Thanks, -- Darren Hart -- http://mail.python.org/mailman/listinfo/python-list
SSE4a with ctypes in python? (gcc __builtin_popcount)
Hi guys,
Here is the sample code
http://stackoverflow.com/questions/6389841/efficiently-find-binary-strings-with-low-hamming-distance-in-large-set/6390606#6390606
static inline int distance(unsigned x, unsigned y)
{
return __builtin_popcount(x^y);
}
Is it possible to rewrite the above gcc code in python using ctypes
(preferably Win/*nix compatible)?
TIA!
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ttk Listbox
What would be an equivalent widget in ttk like a Listbox and if possible a small example? I tried to look here http://docs.python.org/library/ttk.html but did not see anything. Maybe I did not look in the right place? tia -- http://mail.python.org/mailman/listinfo/python-list
