Defending the ternary operator

[Andrew Dalke]

Paul Paterson:
> Continuing the experiment to look at Python code which might use the
> conditional operator....
>
> If my regular expression is correct (and it probably isn't because I'm not
> good at them), then a quick scan of my Python22 directory structure finds
> 769 matches of the following pattern,
>
>     if <something>
>         variable = <some value>
>     else:
>         variable = <some other value>
>
> in 381209 lines of code. I leave the statistical interpretation to the
> reader.

You should also look at C/C++ code and see how many times C
code uses

  if (something) {
    variable = some_value;
  } else {
    variable = some_other_value;
  }

For example, why doesn't this code from CPython's mmapmodule.c
use the ?: operator?

           if (!map_size) {
                   m_obj->size = GetFileSize (fh, NULL);
           } else {
                   m_obj->size = map_size;
           }

After all, C has ?: so isn't this more readable, (insert pro-PEP arguments
here) as

  m_obj->size = !map_size ? GetFileSize(fh, NULL) : map_size;
?

> I intend to post each one with an analysis of why they would or wouldn't
be
> better done using the new form....

Please also include the same analysis for Python's C implementation.  ;)

                    Andrew
                    dalke at dalkescientific.com