Delay evaluation of annotations
Hi all, Annotations of function parameters and variables are evaluated when encountered. This makes it necessary to use string representation for names that are not yet bound, which affects almost every class definition. It is also easy to forget, and the result might be a (very uninteresting) exception in certain untested paths, e.g. inside functions. Editors and IDEs also don't handle it well; for example, PyDev does not consider string-annotations as an occurrence of the name, and warns about unused imports. I propose delaying evaluation of annotation-expressions by either keeping the AST of the annotation, or turning it implicitly from EXP into "lambda: EXP". Inspection code that is interested in this information can access it be calling (or evaluating) it. It certainly isn't a backward compatible change, but I think it won't affect too much code. On the positive side, it will make annotated code much more pleasing to read, will be less surprising for beginners, and will help editors in syntax highlighting and name lookup. In short, it will shift the burden of handling type annotations from standard code to inspection code, which is where I believe it should rest. While this idea is quite obvious, I've found no clue in PEP-3107 as to why will it be a bad one (no such "rejected proposal" there), so I raise the question here. Elazar
participants (15)
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Alexander Belopolsky -
Chris Angelico -
David Mertz -
Greg Ewing -
Ivan Levkivskyi -
Joseph Jevnik -
Neil Girdhar -
Nick Coghlan -
Oleg Broytman -
Paul Moore -
Sjoerd Job Postmus -
Stephen J. Turnbull -
Steven D'Aprano -
Terry Reedy -
אלעזר