[Python-Dev] pep 362 - 5th edition (original) (raw)

Steven D'Aprano steve at pearwood.info
Wed Jun 20 10:15:57 CEST 2012

On Tue, Jun 19, 2012 at 12:38:38PM -0400, Yury Selivanov wrote:

> class Signature: > . . . > def equivalent(self, other): > "compares two Signatures for equality (ignores parameter names)" > . . .

I don't think that comparing signatures will be a common operation, so maybe we can postpone adding any additional methods for that?

I think it may be. Consider callback functions: the caller may wish to check that the callback function takes the right number of positional arguments, but without caring whether those arguments are given any particular name.

Checking for compatible signatures is a little more subtle than just ignoring names. For example, keyword-only arguments need to always be compared by names. Also, you might want to ignore optional arguments with defaults, or at least _private optional arguments.

I think equality should be strict, including names, and we should defer any decision about less-strict comparisons until 3.4, when we'll have more solid use-cases for it.

I guess that's a long-winded way of saying +1 :)

-- Steven

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