[Python-3000] PEP Parade (original) (raw)

Phillip J. Eby pje at telecommunity.com
Tue May 1 21:07:36 CEST 2007

At 11:31 AM 5/1/2007 -0700, Guido van Rossum wrote:

I haven't had the time to read this in detail, but in general I'm feeling favorable about this idea. I'd rather see it decoupled from sys.getframe() and modifying funccode (actually code nowadays, see PEP 3100).

I've figured out how to drop some (but not all) of the _getframe() hackery from the current proposal, btw. (Specifically, I believe I can make the decorators decide which function to return using name comparisons instead of by checking frame contents.)

Regarding code, however, it's either that or allow functions to be subclassed and have their type changed at runtime.

In other words, if you could meaningfully assign to a function's class, then mucking with its code would be unnecessary; we'd just override call in a subclass, and change the class when overloading an existing function.

Unfortunately, I believe that CPython 2.3 and up don't let you change the type of instances of built-in classes, and it's never been possible to subclass the function type, AFAIK.

OTOH, these restrictions may not exist in Jython, IronPython, or PyPy; if they allow you to subclass the function type and change a function's class, then that approach becomes a reasonable implementation choice on those platforms.

Thus, assignment to code might reasonably be considered a workaround for the limitations of CPython in this respect, rather than a CPython-dependent hack. :)

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