[Python-Dev] Quick poll: should help() show bound arguments? (original) (raw)

Zachary Ware zachary.ware+pydev at gmail.com
Sat Jan 25 05🔞19 CET 2014

On Fri, Jan 24, 2014 at 10:07 PM, Larry Hastings <larry at hastings.org> wrote:

(Quick, because apparently nobody reads the long ones!) In Python 3.3:

class C: ... def foo(self, a): pass ... c = C() help(c.foo) shows you the signature "foo(self, a)". As in, it claims it accepts two parameters. The function actually only accepts one parameter, because "self" has already been bound. inspect.signature gets this right: import inspect str(inspect.signature(c.foo)) '(a)' but inspect.getfullargspec does not: inspect.getfullargspec(c.foo) FullArgSpec(args=['self', 'a'], varargs=None, varkw=None, defaults=None, kwonlyargs=[], kwonlydefaults=None, annotations={}) help() gets its text from pydoc. pydoc uses inspect.getfullargspec to produce the signature. When I added support for introspection on builtins, I wanted help() to show their signature too. But inspect.getfullargspec doesn't support introspection on builtins. So I had to use inspect.signature. Which means the behavior is inconsistent: help() on a method of an instance of a builtin class doesn't show "self". FYI, the relevant issues: help(instanceofbuiltinclass.method) does not display self http://bugs.python.org/issue20379 inspect.getfullargspec should use siganture http://bugs.python.org/issue17481 What should it be? A) pydoc and help() should not show bound parameters in the signature, like inspect.signature. B) pydoc and help() should show bound parameters in the signature, like inspect.getfullargspec. I'll tally the results if there's interest. I'd assume a "vote for A" = +1 on A and -1 on B. You can express your vote numerically if you like. I'm voting for A.

I vote A: it makes sense (though B does too, to an extent), and the patch to make help() consistent for Python and C implemented methods is simply removing two lines from pydoc. I'm not sure how convoluted it might become to make it work the other way.

-- Zach

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