[Python-ideas] Definition Symmetry

[MRAB]

On 2013-01-31 16:35, Jason Keene wrote:
> Why do function definitions require parens?
>
>>>> class MyClass:
> ...     pass
> ...
>>>> def my_func:
>    File "<stdin>", line 1
>      def my_func:
>                 ^
> SyntaxError: invalid syntax
>
> This seems to me to break a symmetry with class definitions.  I assume
> this is just a hold off from C, perhaps there is a non-historical reason
> tho.
>
> I believe in the past we've forced parens in list comprehensions to
> create a symmetry between comprehensions/generator expressions.  Why not
> for this?
>
The parentheses are always required when calling the function, so it
makes sense to always require them when defining the function.

The case with class definitions is different; they are used in the
definition only when you want to specify the superclass.

They are always required when creating an instance of the class and in
method definitions.