Christian Heimes wrote:
> Terry Reedy wrote:
>> One of the nice features of 3.0 is that differences between classes
>> defined in C and Python (other than speed) are mostly erased or hidden
>> from the view of a Python programmer.
>>
>> However, there are still sometimes surprising and quite visible
>> differences between 'functions' written in C and Python. Can these be
>> better unified also?
>>
>> In particular, built-in functions, in spite of of being labeled
>> 'builtin_function_or_method', are not usable as methods because they
>> lack the __get__ method needed to bind function to instance.
>
> Python is far too late in the release cycle to introduce a drastic
> change.
Of course. I should have been clear that I was asking for 3.1.
> The issues has been discussed about half a year ago and we
> decided against changing PyCFunction.
I did't remember that. Was it a permanent or provisional decision.
> But it was a good thing that you've raises your concern. I totally
> forgot about the new instancemethod type. My code is still in
> classobject.c but it's not exposed to Python level. IIRC the
> Pyrex/Cython guys are in need of such a feature.
>
> Patch:
>
> --- Python/bltinmodule.c (revision 66222)
> +++ Python/bltinmodule.c (working copy)
> @@ -2301,6 +2301,7 @@
> SETBUILTIN("frozenset", &PyFrozenSet_Type);
> SETBUILTIN("property", &PyProperty_Type);
> SETBUILTIN("int", &PyLong_Type);
> + SETBUILTIN("instancemethod", &PyInstanceMethod_Type);
> SETBUILTIN("list", &PyList_Type);
> SETBUILTIN("map", &PyMap_Type);
> SETBUILTIN("object", &PyBaseObject_Type);
>
> Result:
>
> $ ./python
> Python 3.0b3+ (py3k:66222M, Sep 5 2008, 02:24:22)
> [GCC 4.2.3 (Ubuntu 4.2.3-2ubuntu7)] on linux2
> Type "help", "copyright", "credits" or "license" for more information.
> >>> class Example:
> ... id = instancemethod(id)
> ...
> >>> example = Example()
> >>> example.id() == id(example)
> True
I consider that 2nd best but it will solve the problem once one is aware
of it. I am thinking of suggesting a new paragraph for the Built-in
Functions sections warning of differences between built-in functions and
function instances.
Terry
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