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

[Jp Calderone]

On Sat, Feb 08, 2003 at 03:14:20PM +0000, Dale Strickland-Clark wrote:
> Anthony Baxter <anthony at interlink.com.au> wrote:
> 
> >This might be fine, but if you start getting listcomps with one of
> >these ternary operators, and an if clause in the listcomp. you're 
> >going to be leaving someone with a hellish ugly bit of code to read.
> >
> >
> >Why not simply:
> >
> >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.

  Jp

-- 
Seduced, shaggy Samson snored.
She scissored short.  Sorely shorn,
Soon shackled slave, Samson sighed,
Silently scheming,
Sightlessly seeking
Some savage, spectacular suicide.
                -- Stanislaw Lem, "Cyberiad"
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