[PyQt] Suggestion: connect overloaded signal based on callable signature (as returned by inspect.signature)

[Phil Thompson]

On 16 Jan 2016, at 7:07 am, Antony Lee <antony.lee at berkeley.edu> wrote:
> 
> Consider the following example:
> 
> from functools import wraps
> from PyQt4.QtCore import *
> from PyQt4.QtGui import *
> 
> def decorator(func):
>     @wraps(func)
>     def wrapper(*args, **kwargs):
>         return func(*args, **kwargs)
>     return wrapper
> 
> class C(QComboBox):
>     @decorator
>     def method(self):
>         print("here")
> 
> app = QApplication([])
> c = C()
> c.activated.connect(c.method)
> c.activated.emit(1)
> 
> This fails (also under PyQt5) with "TypeError: method() takes 1 positional argument but 2 were given", i.e. the connection was made using the "activated[int]" signal overload.  But the actual signature of "c.method" (as taking no argument) is in fact available (since Python 3.3) via "inspect.signature".
> 
> I am thus suggesting to rely on "inspect.signature" for the overload resolution.  (I am aware that decorating with pyqtSlot() can also resolve the ambiguity.)
> 
> Thoughts?

At this stage it would be a lot of effort (to parse the signature and translate it into an equivalent C++ version) for little benefit.

Had this been available when pyqtSlot() was invented, then it might have been worth it.

Phil