On 3/6/2014 1:59 PM, Tim Chase wrote:
On 2014-03-06 03:34, candide wrote:
According to the official documentation, the ternary operator has
left-to-right associativity
left_to_right = (0 if 1 else 0) if 0 else 1
right_to_left = 0 if 1 else (0 if 0 else 1)
I'd never want to rely on my own ability to remember the language
spec, so I strongly advocate for making it explicit with parens
regardless of what the language defines. And that's if I ever created
such a mess in the first place. If you have more than one pair of
conditional expressions in a single assignment, I'd suggest that it's
a code-smell that could use refactoring for clarity/disambiguity.
It is intended and part of the PEP discussion that one be able to write
chained conditional expression in Python
x = (a1 if c1 else
a2 if c2 else
a3 if c3 else
a4)
without extra ()s, similar to what one can write in C (if I remember
correctly)
x = c1 ? a1 :
c2 ? a2 :
c3 ? a3 :
a4
both being abbreviations for chained if-elses
if c1: x = a1
elif c2: x = a2
elif c3: x = a3
else: x = a4
In all three cases, the conditions are evaluated in 1,2,3 order, each
before the corresponding expression.
--
Terry Jan Reedy
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