[Python-ideas] PEP 484 (Type Hints) -- first draft round

Terry Reedy tjreedy at udel.edu
Sun Jan 18 00:36:26 CET 2015


On 1/16/2015 4:40 PM, Guido van Rossum wrote:
> On Fri, Jan 16, 2015 at 12:34 PM, Dennis Brakhane

>     I feel there should be another way to make type annotations and
>     "creative" annotations coexist.
>
> The cleanest way to do this would be to use decorators for the
> non-type-hint use case.

I have come to agree with this as the least bad solution.  From a 
runtime perspective, annotation syntax is merely a nice way to attach to 
a function an attribute whose value is a dict whose keys are function 
and parameter names.  Decorators can do the same (and have been able to 
do so since introduced).  Repeating (and quoting) names in the decorator 
is a nuisance, but as a reader, I would prefer that to having multiple 
annotation systems mixed together.  The decorator solution, with custom 
attribute names, scales better to multiple annotation systems.

-- 
Terry Jan Reedy



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