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

[William Park]

Jp Calderone <exarkun at intarweb.us> wrote:
>> >def condsqrt(z):
>> >  if z > 0.0: 
>> >    return sqrt(z)
>> >  else:
>> >    return 0.0
>> >
>> >y = [ condsqrt(z) for z in x ]
>> >
>> >There's a function call overhead, but it's a hell of a lot easier to
>> >read.
>> 
>> No. Splitting an expression so it's spread over your code is a very
>> good way of introducing inefficiencies and bugs. And now the reader
>> has to hunt around looking for the function to understand what's
>> going on.
> 
>  No, it's what structured program is *all* *about*.  Picking useful
>  pieces of behavior out and abstracting them (often with a function).
>  Furthermore, say you make a mistake (unlikely in *this* trivial case,
>  I admit).  Do you want to fix it in one place, the condsqrt function
>  definition, or in 30 places, in 15 different source files?
> 
>  No, splitting algorithms up is a very *good* idea.

To a certain point.  For the silly example above, 
    (z>0.0) ? sqrt (z) : 0.0
would do nicely.

-- 
William Park, Open Geometry Consulting, <opengeometry at yahoo.ca>
Linux solution for data management and processing.