[Python-3000] Draft pre-PEP: function annotations

[Greg Ewing]

Collin Winter wrote:
>    one library might use string-based annotations to provide
>    improved help messages, like so:
>
>         def compile(source: "something compilable",
>                     filename: "where the compilable thing comes from",
>                     mode: "is this a single statement or a suite?"):
> 
>    Another library might be used to provide typechecking for Python
>    functions and methods.
>
>         def sum(*vargs: Number) -> Number:
>             ...

And what are you supposed to do if you want to write
a function that has improved help messages *and*
type checking?

>    The difficulty inherent in writing annotation interpreting
>    libraries will keep their number low and their authorship in the
>    hands of people who, frankly, know what they're doing.

Even if there are only two of them, they can still
conflict.

I think the idea of having totally undefined
annotations is fundamentally flawed.

--
Greg