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

Maciej Fijalkowski fijall at gmail.com
Fri Jul 2 08:38:11 CEST 2010

On Fri, Jul 2, 2010 at 12:31 AM, Stefan Behnel <stefan_ml at behnel.de> wrote:

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

This question has an easy answer - can you possibly tell the difference?

Cheers, fijal

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