[Python-Dev] conditional expressions - add parens? (original) (raw)

Steve Holden steve at holdenweb.com
Mon Mar 6 22:34:51 CET 2006

Jim Jewett wrote:

Now that we have started to see conditional expressions ... I would like to see them parenthesized. The parens aren't as important as they are with generator expressions, but ... they matter.

From a recent checkin -- level = 0 if "absoluteimport" in self.futures else -1 Personally I think the above code exemplifies exactly why Guido was correct in his reluctance to add conditional expressions.

Mentally, I can't help parsing that as "level = 0" plus comments that turn out to be code that triggers backracking.

When the expressions (particularly the true case) are longer, it gets even worse. I think that adding parentheses would help, by at least signalling that the logic is longer than just the next (single) expression. level = (0 if "absoluteimport" in self.futures else -1) Contrast with the bleeding obvious:

 level = 0
 if "absolute_import" in self.futures:
     level = -1

or even, if a certain obscurity is desirable:

 level = - ("absolute_import" in self.futures)

regards Steve

Steve Holden +44 150 684 7255 +1 800 494 3119 Holden Web LLC/Ltd www.holdenweb.com Love me, love my blog holdenweb.blogspot.com

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