[Python-Dev] Adding a conditional expression in Py3.0

Steve Holden steve at holdenweb.com
Thu Sep 29 23:32:06 CEST 2005

Guido van Rossum wrote:
> On 9/29/05, Steve Holden <steve at holdenweb.com> wrote:
>>I would argue for mandatory parentheses around the expression, leaving
>>room later (probably after Guido is no longer around to be sick at the
>>site of it) for:
>>def f(condition):
>>     return something if condition # no else!
>>     return somethingElse
>>not-expecting-this-to-fly-ly y'rs  - steve
> Let me give you what you expect. If all the "X if C else Y" syntax
> does is prevent that atrocity from ever being introduced, it would be
> worth it. :)
Well, fine. However, it does allow atrocities like

func(f for f in lst if f > -1 if f < 0 else +1)

I realise that any chosen syntax is subject to abuse, but a conditional 
expression in a (currently allowed) conditional context will be 
guaranteed obscure. Your original instinct to omit conditional 
expressions was right!

far-too-late-ly y'rs  - steve
Steve Holden       +44 150 684 7255  +1 800 494 3119
Holden Web LLC                     www.holdenweb.com
PyCon TX 2006                  www.python.org/pycon/

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