[Python-Dev] Can/should built-in functions get get? (original) (raw)

Terry Reedy tjreedy at udel.edu
Fri Sep 5 08:43:17 CEST 2008

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 'builtinfunctionormethod', 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", &PyFrozenSetType); SETBUILTIN("property", &PyPropertyType); SETBUILTIN("int", &PyLongType); + SETBUILTIN("instancemethod", &PyInstanceMethodType); SETBUILTIN("list", &PyListType); SETBUILTIN("map", &PyMapType); SETBUILTIN("object", &PyBaseObjectType); 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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