no unbound methods in py3k

[Thomas Heller]

I'm currently using code like this to create unbound methods
from functions and stick them into classes:

method = new.instancemet hod(raw_func, None, cls)
setattr(cls, name, method)

Ok, python 2.6, run with the -3 flag, gives a warning that the new
module is going away in python 3.0, so the equivalent code is:

method = types.MethodTyp e(raw_func, None, cls)
setattr(cls, name, method)

However, this code will not work in Python 3.0 because there are
no unbound methods any longer. The only way that I found so far
is this code:

method = lambda self, *args: raw_func(self, *args)
setattr(cls, name, method)

or the equivalent:

def method(self, *args):
return raw_func(self, *args)
setattr(cls, name, method)

but this is very ugly, imo. Is there another way?
The raw_func instances that I have are not descriptors (they
do not implement a __get__() method...)

Thanks,
Thomas

[Christian Heimes]

Re: no unbound methods in py3k

Thomas Heller wrote:

but this is very ugly, imo. Is there another way?
The raw_func instances that I have are not descriptors (they
do not implement a __get__() method...)

I've written PyInstanceMetho d_Type for this use case. It's not (yet)
available for Python code. Barry hasn't decided whether he should expose
the type so late in the release cycle or not. See
http://bugs.python.org/issue3787 and

http://docs.python.org/dev/3.0/c-api/method.html?highlight=pyinstancemethod#PyInstanceMethod_Type

Christian

[Thomas Heller]

Re: no unbound methods in py3k

Christian Heimes schrieb:

Thomas Heller wrote:

>but this is very ugly, imo. Is there another way?
>The raw_func instances that I have are not descriptors (they
>do not implement a __get__() method...)

>
I've written PyInstanceMetho d_Type for this use case. It's not (yet)
available for Python code. Barry hasn't decided whether he should expose
the type so late in the release cycle or not. See
http://bugs.python.org/issue3787 and

http://docs.python.org/dev/3.0/c-api/method.html?highlight=pyinstancemethod#PyInstanceMethod_Type

>

Ok, so one has to write an extension to access or expose it.

Oh, wait - there's ctypes:

Python 3.0rc1 (r30rc1:66507, Sep 18 2008, 14:47:08) [MSC v.1500 32 bit (Intel)] on win32
Type "help", "copyright" , "credits" or "license" for more information.

>>from ctypes import *
>>pythonapi.PyI nstanceMethod_N ew.restype = py_object
>>pythonapi.PyI nstanceMethod_N ew.argtypes = [py_object]
>>instancemetho d = pythonapi.PyIns tanceMethod_New
>>>
>>class Example:

.... pass
....

>>Example.id = instancemethod( id)
>>>
>>x = Example()
>>x.id()

12597296

>>id(x)

12597296

>>>

Thomas

[Terry Reedy]

Re: no unbound methods in py3k

Thomas Heller wrote:

Christian Heimes schrieb:

>Thomas Heller wrote:

>>but this is very ugly, imo. Is there another way?
>>The raw_func instances that I have are not descriptors (they
>>do not implement a __get__() method...)

>I've written PyInstanceMetho d_Type for this use case. It's not (yet)
>available for Python code. Barry hasn't decided whether he should expose
>the type so late in the release cycle or not. See
>http://bugs.python.org/issue3787 and
>http://docs.python.org/dev/3.0/c-api...nceMethod_Type
>>

>
Ok, so one has to write an extension to access or expose it.
>
Oh, wait - there's ctypes:
>
Python 3.0rc1 (r30rc1:66507, Sep 18 2008, 14:47:08) [MSC v.1500 32 bit (Intel)] on win32
Type "help", "copyright" , "credits" or "license" for more information.

>>>from ctypes import *
>>>pythonapi.Py InstanceMethod_ New.restype = py_object
>>>pythonapi.Py InstanceMethod_ New.argtypes = [py_object]
>>>instancemeth od = pythonapi.PyIns tanceMethod_New
>>>>
>>>class Example:

... pass
...

>>>Example.id = instancemethod( id)
>>>>
>>>x = Example()
>>>x.id()

12597296

>>>id(x)

12597296

A pyCapi module that exposed via ctypes useful C functions not otherwise
accessible, with predefinition of restype and argtypes and anything else
needed, might make a nice addition to PyPI if not the stdlib. You have
done two here and I believe others have posted others.

tjr

[Thomas Heller]

Re: no unbound methods in py3k

Terry Reedy schrieb:

Thomas Heller wrote:

>Christian Heimes schrieb:

>>I've written PyInstanceMetho d_Type for this use case. It's not (yet)
>>available for Python code.>Oh, wait - there's ctypes:

>>
>Python 3.0rc1 (r30rc1:66507, Sep 18 2008, 14:47:08) [MSC v.1500 32 bit (Intel)] on win32
>Type "help", "copyright" , "credits" or "license" for more information.

>>>>from ctypes import *
>>>>pythonapi.P yInstanceMethod _New.restype = py_object
>>>>pythonapi.P yInstanceMethod _New.argtypes = [py_object]
>>>>instancemet hod = pythonapi.PyIns tanceMethod_New
>>>>>
>>>>class Example:

>... pass
>...

>>>>Example.i d = instancemethod( id)
>>>>>
>>>>x = Example()
>>>>x.id()

>12597296

>>>>id(x)

>12597296

>
A pyCapi module that exposed via ctypes useful C functions not otherwise
accessible, with predefinition of restype and argtypes and anything else
needed, might make a nice addition to PyPI if not the stdlib. You have
done two here and I believe others have posted others.

Well, Lenard Lindstrom has some time ago contributed a module like that
which is available in the (more or less unmaintained) ctypeslib project:

http://svn.python.org/projects/ctypes/trunk/ctypeslib/ctypeslib/contrib/pythonhdr.py

However, it was probably more meant to provide a complete Python C api,
instead of concentrating on stuff not available to Python otherwise.

Thomas

[Christian Heimes]

Re: no unbound methods in py3k

Thomas Heller wrote:

Ok, so one has to write an extension to access or expose it.
>
Oh, wait - there's ctypes:

I wrote the type to help the Pyrex and Cython developers to port their
software to 3.0. I planed to expose the type as
__builtin__.ins tancemethod but forgot it. Maybe we can convince Barry
together. He still considers my bug as a release blocker for 3.0.

Christian

[Thomas Heller]

Re: no unbound methods in py3k

Christian Heimes schrieb:

Thomas Heller wrote:

>Ok, so one has to write an extension to access or expose it.
>>
>Oh, wait - there's ctypes:

>
I wrote the type to help the Pyrex and Cython developers to port their
software to 3.0. I planed to expose the type as
__builtin__.ins tancemethod but forgot it. Maybe we can convince Barry
together. He still considers my bug as a release blocker for 3.0.
>

Issue 3787 is marked as release blocker, but for 3.1 IIUC. Would it help
if I post my use case to the tracker?

Thomas