For review: PEP 308 - If-then-else expression

John Hazen python-list at hazen.net
Sun Feb 9 10:05:57 CET 2003


I'm a python newbie (written ~100 lines of python and read c.l.py for a couple
of weeks), and I wanted to weigh in on the clarity of the proposal.

I found it intuitive and easy to understand.  I like the order that Guido has
proposed, and disagree with those who claim it doesn't read luft-to-right.
It's just the way I would say it in english:

My activity is "eating" if I'm hungry, otherwise I'll be "reading c.l.py".
myActivity = "eating" if hungry else "reading c.l.py"


I want to caution against making the else clause optional, as it blurs the
distinction between the conditional _operator_ and the conditional _statement_.

Most of you seem to interpret 
>>> activity = "eating" if hungry

to mean:
>>> activity = "eating" if hungry else None
(obvious default if you know it's conditional _evaluation_)

But, as a future former perl programmer, to me this means:
>>> activity = "eating" if hungry else activity
(default if you think it's conditional _execution_; the variable
retains its former value.)

I'm in favor of the PEP.

John
-- 
John Hazen              
john at my domain (see headers)





More information about the Python-list mailing list