[Python-Dev] signature object issues (to discuss while I am out of contact) (original) (raw)

Aahz aahz at pythoncraft.com
Tue May 2 05:49:34 CEST 2006

On Mon, May 01, 2006, Brett Cannon wrote:

On 5/1/06, Aahz <aahz at pythoncraft.com> wrote:

On Mon, May 01, 2006, Brett Cannon wrote:

But there are two things that I can't quite decide upon. One is whether a signature object should be automatically created for every function. As of right now the PEP I am drafting has it on a per-need basis and have it assigned to signature through a built-in function or putting it 'inspect'. Now automatically creating the object would possibly make it more useful, but it could also be considered overkill. Also not doing it automatically allows signature objects to possibly make more sense for classes (to represent init) and instances (to represent call). But having that same support automatically feels off for some reason to me. My take is that we should do it automatically and provide a helper function that does additional work. The class case is already complicated by new(); we probably don't want to automatically sort out init() vs new(), but I think we do want regular functions and methods to automatically have a signature attribute. Aside from the issue with classes, are there any other drawbacks to automatically creating signature? Well, one issue is the dichotomy between Python and C functions not both providing a signature object. There is no good way to provide a signature object automatically for C functions (at least at the moment; could add the signature string for PyArgParseTuple() to the PyMethodDef and have it passed in to the wrapped C function so that initialization of the class can get to the parameters string). So you can't fully rely on the object being available for all functions and methods unless a worthless signature object is placed for C functions.

From my POV, that suggests changing the C API rather than not having automatic signatures. That probably requires Py3K, though.

Aahz (aahz at pythoncraft.com) <*> http://www.pythoncraft.com/

"Argue for your limitations, and sure enough they're yours." --Richard Bach

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