New submission from Yury Selivanov:
There is a small detail in the current Signature class implementation, in
regards to how partial signatures are treated. Consider the following example:
def foo(a, b): pass
foo_partial = functools.partial(foo, 'spam')
Now, the signature of
R. David Murray added the comment:
I believe it is a python invariant that a == b implies hash(a) == hash(b). I
don't see why the two signatures should be equal. I'm not even sure why the
bound argument shows up in the signature of the partial. That surprises me.
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nosy:
Nick Coghlan added the comment:
On 1 Apr 2014 07:36, Nick Coghlan rep...@bugs.python.org wrote:
Nick Coghlan added the comment:
The already bound arguments should be treated as additional keyword-only
arguments, and already bound positional arguments hidden completely.
Oops: already bound
Yury Selivanov added the comment:
@Nick:
Oops: already bound positional-*only* arguments should be hidden.
Hm, good catch. I'm not sure we currently do this. I'll check if this needs to
be fixed (in 3.4.1 too).
I'm +0 on new types to clean that up if necessary, but would prefer it if
we
Nick Coghlan added the comment:
On 1 Apr 2014 08:17, Yury Selivanov rep...@bugs.python.org wrote:
I'm +0 on new types to clean that up if necessary, but would prefer it
if
we could just improve the translation to ordinary signature objects
instead.
I'm not sure I understand what you mean
Yury Selivanov added the comment:
@Nick:
Agreed on positional-only stuff.
If arguments bound by position disappear from the signature, and those
bound by keyword are mapped to keyword-only parameters with a default, we
should get a valid and accurate signature.
But what about my example
Yury Selivanov added the comment:
@Nick: oh, it took me some time to realize that your suggestion to transform
positional-or-keyword to keyword-only parameters is correct. If we do this, we
no longer need '_partial_kwarg' hack. I'll work on the patch. Thank you.
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