On 31 August 2016 at 15:40, Guido van Rossum <guido@python.org> wrote:
On Tuesday, August 30, 2016, Nick Coghlan <ncoghlan@gmail.com> wrote:
What if we included local variable annotations in func.__annotations__ as cells, like the entries in func.__closure__?
We could also use that as a micro-optimisation technique: once the type annotation cell is populated, CPython would just use it, rather than re-evaluating the local variable type annotation expression every time the function is called.
But what runtime use have the annotations on locals? They are not part of any inspectable interface. I don't want to spend any effort on them at runtime. (Just the bit that they are treated as locals.)
I guess as long as they're included somewhere in the AST for the function body, I don't mind if the translation to bytecode throws them away - that's essentially saying that a function level type annotation is effectively interpreted as if it was: if False: __annotations__[<varname>] = <annotation> So the code generator will pick up syntax errors during normal execution, but not runtime errors (since the expression never actually gets evaluated). Cheers, Nick. -- Nick Coghlan | ncoghlan@gmail.com | Brisbane, Australia