[Python-Dev] PEP 526 ready for review: Syntax for Variable and Attribute Annotations

[Wolfgang]

Hi,

first if something like this is needed I am fine with the syntax.

But I think this changes comes to late for 3.6. There is more time needed
to discuss all of this and there is more time needed to mature the type
checkers. Don't rush with such a change because it affects the language at whole.
So please defer it.

Saying the syntax is fine means not I am happy with the addition.
Fundamentally I think don't add this at Python language syntax level.
Years come and it will be misused misunderstood by new users.
It will affect all other users reading the code and even misguiding them.

If Variable and Attribute Annotation is needed keep it simply at the
stub file level on *.pyi files. Only there for the type checking stuff.
Other users must not bother with them.

And for stub files it can be as simple as:

myvar = typing.Int()

or all other valid syntax.


For me the whole specifying of types in Python comes down to:
It can be useful to document a user interface (most of the time a function
or method) and say if you call it these types are supported.

At some day a documentation generator can use this type information
and I have no longer the need to specify it also in the docstring.

Personally I would like to extend the pyi stub files to carry also the
documentation and keep the code as clean and short as possible.
Sometimes the documentation is longer than the code and the code is no longer
easy to find.
Instead of putting everything into the language put more into the stub files.
Even micropython or other implementations with limited constraints don't need
to carry all of this. Even if it is only part of the AST, it is overhead.


Have someone checked if there is a possibility if this is added to slow
down the interpreter or interpreter startup or increase the memory
consumption?


Regards,

Wolfgang


On 30.08.2016 23:20, Guido van Rossum wrote:
> I'm happy to present PEP 526 for your collective review:
> https://www.python.org/dev/peps/pep-0526/ (HTML)
> https://github.com/python/peps/blob/master/pep-0526.txt (source)
> 
> There's also an implementation ready:
> https://github.com/ilevkivskyi/cpython/tree/pep-526
> 
> I don't want to post the full text here but I encourage feedback on
> the high-order ideas, including but not limited to
> 
> - Whether (given PEP 484's relative success) it's worth adding syntax
> for variable/attribute annotations.
> 
> - Whether the keyword-free syntax idea proposed here is best:
>   NAME: TYPE
>   TARGET: TYPE = VALUE
> 
> Note that there's an extensive list of rejected ideas in the PEP;
> please be so kind to read it before posting here:
> https://www.python.org/dev/peps/pep-0526/#rejected-proposals-and-things-left-out-for-now
> 
>