Re: [O] Re: Yahoo is moving to PHP ??

[Perrin Harkins]

Franck PORCHER wrote:

But <for> is a lot easier to read and debug, IMHO .... Is there a
significant performance difference in using map instead?

My experience is that in most cases, the <for> construct is used
to apply the same treatment to all the elements of an array,
whence the <map> construct. In those cases, the readibility
is definitely altered by the index that get
in the way.

I think you're forgetting that "for" is just a synonym for "foreach". You don't need an index.

Of course, this is a quick analysis not taking into account other
factors like readibility versus efficiency.

In fact, regarding the efficiency of the <map> construct,
I often wondered whether Perl detects <map> being ran in a void context, so as
to give it an iterative interpretation, avoiding to build the output
list.

It's really not a matter of efficiency, but rather of correctness. Using map in a void context is a mistake. There is a time and place for map: when you want to do something to each element in an array and return the array on the other side. Otherwise, use for, like this:

some_function($_) for @array;.

Even when map is not incorrect, I usually avoid it because it has a tendency to take your code from nice, readable perl to evil h@x0r PERL in 3 characters. This is the kind of thing that Yahoo was probably worried about when the decided not to use Perl.

- Perrin