On Tue, Apr 21, 2015 at 4:46 PM, Paul Rubin <no.email@nospam.invalid> wrote: > Chris Angelico <ros...@gmail.com> writes: >> Ow, this is getting extremely complicated. And you still haven't >> actually answered the fundamental problem, which is: When will you >> need this? When will you actually want to put two different >> annotations onto the same function's parameters? > > You've posted this cool annotation for docstringargs: why shouldn't I > want to use it? And PEP 0484 is about annotations for type checking, > also cool. Why shouldn't I want to use that too?
Except that docstringargs is mainly for top-level functions, and PEP 484 / MyPy is mainly for library functions - plus, docstringargs basically implies that all the function parameters are strings, so the annotations are going to be rather less useful. >> The language isn't going to get any type checking. > > I thought it was one of the motivations for annotations. PEP 0484 > explains: > > ... the proposal assumes the existence of a separate off-line type > checker which users can run over their source code voluntarily. > > That sounds like Erlang's Dialyzer, which is pretty useful and > successful. So it seems like a good idea to me. Off-line. Not part of the language itself. PEP 484 is standardizing a format for them, but actually using them is staying the domain of third-party utilities like MyPy. Nothing at all changes in the language (annotations already exist), and the stdlib just grows a typing.py that provides enough run-time so that things don't give errors, but nothing in a basic CPython installation will do those checks. Hence it's up to you what you do with them; simply running a program won't check type annotations in any way. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
