[Python-Dev] Python equivalents in stdlib Was: Include datetime.py in stdlib or not?

[Antoine Pitrou]

On Wed, 07 Jul 2010 21:45:30 -0400
Terry Reedy <tjreedy at udel.edu> wrote:
> 
> > Except that ctypes doesn't help provide C extensions at all. It only
> > helps provide wrappers around existing C libraries, which is quite a
> > different thing.
> > Which, in the end, makes the original suggestion meaningless.
> 
> To you, so let me restate it. It would be easier for many people to only 
> rewrite, for instance,  difflib.SequenceMatcher.get_longest_matching in 
> C than to rewrite the whole SequenceMatcher class, let alone the whole 
> difflib module.

And you still haven't understood my point. ctypes doesn't allow you to
write any C code, only to interface with existing C code. So,
regardless of whether get_longest_matching() is a function or method,
it would have to be written in C manually, and that would certainly be
in an extension module.
(admittedly, you can instead make a pure C library with such a function
and then wrap it with ctypes, but I don't see the point: you still have
to write most C code yourself)

> I got the impression from the datetime issue tracker discussion that it 
> is not possible to replace a single method of a Python-coded class with 
> a C version.

And that's a wrong impression. Inheritance allows you to do that (see
Michael's answer).
Besides, you can also code that method as a helper function. It is not
difficult to graft a function from a module into another module.

Antoine.