"?:", "a and b or c" or "iif"

[Graham Matthews]

news.eunet.no (Hans-Christian.Holm at nrk.no) wrote:
: Python uses :, but what about a builtin "iif"? This function exists in other
: languages, and is easy to implement:
: 
: def iif(x, a, b):
:   if x:
:     return a
:   else:
:     return b
: 
: I use it quite often, as it does make the code a lot cleaner when the
: functionality is needed many times in a program. 

But the above code is not equivalent to a "condt ? a : b" construct
as you suggested. Why? Your "iif" function evaluates both "a" and "b"
since function arguments are evaluated before function calls. The "?"
construction only evaluates one of "a" and "b". 

graham

-- 
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                 Black velvet and a soft southern sky
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