[Python-ideas] Define a method or function attribute outside of a class with the dot operator

[Stephan Houben]

What about using a simple decorator instead?

def monkey_patch(cls):
    return lambda func: setattr(cls, func.__name__, func)

class Foo:
   pass

@monkey_patch(Foo)
def bar(self):
    return 42

Foo().bar()
# gives 42

2017-02-10 11:15 GMT+01:00 Matthias welp <boekewurm at gmail.com>:

> Hi Markus,
>
> Thanks for writing this up, as I've had this same very valid problem
> before.
>
> On 10 February 2017 at 10:13, Markus Meskanen <markusmeskanen at gmail.com>
> wrote:
> > I'm suggesting the addition of support to using a dot notation when
> defining
> > a function to be a method of a class, or a callback attribute.
>
> Your solution to me seems like a 'hack': class monkey-patching during
> runtime
> is already available if you really need it, and your proposal only
> makes it easier,
> which I don't really like.
>
> > This functionality would be useful in the few rare cases where the class
> > itself needs to be accessed in the function's definition (decorator,
> typing,
> > etc
>
> This problem could just as well be solved by allowing access to a
> scope-level
> variable (__class__? __type__?) which is available in the class body at
> construction time, which points to the (eventual) class type object,
> or evaluating
> the type hints in a class only after the class is created, which then
> allows for that
> class to be pointed to in the type annotations.
>
> E.G. this does not work right now:
>
>     class A:
>         def foo(self: A):
>             pass
>
> as it fails with NameError: A is not defined, whereas you'd expect it to
> work.
>
> The problem is very annoying when you're trying to work with the dunder
> methods for e.g. numerical objects, as you cannot say '+ is only allowed
> for
> these types', but it is not limited to this scope only.
>
>
> -Matthias
> _______________________________________________
> Python-ideas mailing list
> Python-ideas at python.org
> https://mail.python.org/mailman/listinfo/python-ideas
> Code of Conduct: http://python.org/psf/codeofconduct/
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/python-ideas/attachments/20170210/a066c2de/attachment-0001.html>