[Python-ideas] Continuation of `__name__` or a builtin function for general name getting

[Chris Angelico]

On Mon, Jun 19, 2017 at 7:38 AM, Alireza Rafiei
<alireza.rafiei94 at gmail.com> wrote:
> I'm not sure whether this idea has been discussed before or not, so I
> apologize in advanced if that's the case.
>
> Consider the behavior:
>
>> >>> f = lambda: True
>> >>> f.__name__
>> '<lambda>'
>> >>> x = f
>> >>> x.__name__
>> '<lambda>'
>
>
> I'm arguing the behavior above is too brittle/limited and, considering that
> the name of the attribute is `__name__`, not entirely consistent with
> Python's AST. Consider:
>
>> >>> f = lambda: True
>> >>> x = f
>
>
> At the first line, an ast.Assign would be created whose target is an
> ast.Name whose `id` is `f`.
> At the second line, an ast.Assign would be created whose target is an
> ast.Name whose `id` is `x`.

The __name__ of a function has nothing to do with an Assign node,
which is simply assigning a value to something. For instance, if you
do:

>>> f = "hello"

you wouldn't expect the string "hello" to have a __name__ - it's just
a string. And a lambda function normally won't be assigned to
anything. You use lambda when there isn't any name:

>>> do_stuff(lambda q: q * 2 + 1)

and you use def when you want to assign it to a name:

>>> def f(): return True

By the time the Assign operation gets performed, the function object -
with all of its attributes, including __name__ - has been completely
created. I'm not sure what your proposal would do to these kinds of
situations, but it shouldn't be modifying the assigned object.

ChrisA