[Python-Dev] Adding a conditional expression in Py3.0 (original) (raw)

Terry Reedy tjreedy at udel.edu
Wed Sep 21 00:24:27 CEST 2005

"Guido van Rossum" <guido at python.org> wrote in message news:ca471dc2050920121778df3fcd at mail.gmail.com...

On 9/20/05, Terry Reedy <tjreedy at udel.edu> wrote:

Given the later addition of generator expressions with mandatory parentheses , the mandatory-parentheses version of a conditional expression looks less strange to me than it did then ;-). So I could happily use it even though I may still lean toward the other option 2 version (then-else) due to its not needing ':'s or a third elseif term for chaining. I think I'd prefer (if then else ) i.e. no colons. None of the other expression forms (list comprehensions and generator expressions) involving statement keywords use colons.

I presume this revision would continue to include elif clauses. If I put on a 'designing Python for everyone' hat, then the presence of the leading 'if' looks better than the slightly-too-cute (especially for Python) abbreviated version. +1

If you want general community input, I would suggest a runoff ballot with those four choices (and a summary of pros and cons of each), or fewer if you see any as unacceptible. If there's one thing I've learned from the PEP 308 vote, it is that votes for language don't work. I prefer some discussion on Python-dev after which I pick one.

If we reject both the status quo and the symbol-tax form and agree on the above as the best wordy form, then it is a moot point anyway ;-)

C.l.p. newcomers continue to periodically request "How do I write conditional expressions?". I think most will be happier with something clear and readable.

Terry J. Reedy

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