[Python-Dev] Can Python implementations reject semantically invalid expressions? (original) (raw)

Stefan Behnel stefan_ml at behnel.de
Fri Jul 2 08:31:21 CEST 2010

Glyph Lefkowitz, 02.07.2010 06:43:

On Jul 2, 2010, at 12:28 AM, Steven D'Aprano wrote:

This question was inspired by something asked on #python today. Consider it a hypothetical, not a serious proposal.

We know that many semantic errors in Python lead to runtime errors, e.g. 1 + "1". If an implementation rejected them at compile time, would it still be Python? E.g. if the keyhole optimizer raised SyntaxError (or some other exception) on seeing this: def f(): return 1 + "1" instead of compiling something which can't fail to raise an exception, would that still be a legal Python implementation? I'd say "no". Python has defined semantics in this situation: a TypeError is raised.

So, would it still be Python if it folded

 1 + "1"

into

 raise TypeError()

at compile time?

Stefan

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