map vs. foreach

rchiav has asked for the wisdom of the Perl Monks concerning the following question:

Probably a stupid question, but from a style standpoint, and perhaps an efficiency standpoint, to do something as simple as print the contents of a list, is it prefrable to use map or foreach. Example:

while (my @fields = (getpwent)[6,7]) {
  map {print "$_\n"} @fields;
  print ("-" x 80);
}
[download]

vs.

while (my @fields = (getpwent)[6,7]) {
  foreach my $item (@list) {
   print "$_\n";
  }
  print ("-" x 80);
}
[download]

Just curious..
Rich

Comment on map vs. foreach Select or Download Code

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Re (tilly) 1: map vs. foreach by tilly (Archbishop) on Apr 25, 2001 at 07:39 UTC
If you are not using the return, don't use a map. That said I would write your example as: `while (my @fields = (getpwent)[6,7]) { print map "$_\n", @fields, ("-" x 80); }` [download] (print is quite happy taking a list...)	[reply] [d/l]
Re: map vs. foreach by nardo (Friar) on Apr 25, 2001 at 07:07 UTC
From a style standpoint, I consider foreach to generally be better than map. For this particular problem, I would use `print join("\n", @fields), "\n";` rather than a map or foreach.	[reply] [d/l]
Re: map vs. foreach by hdp (Beadle) on Apr 25, 2001 at 07:39 UTC
`map` in void? Are you trying to invoke merlyn's wrath? :) Consider also: `while (...) { local ($, = $\ = "\n"); print @fields, "-" x 80; }` [download] This is hypothetically "less maintainable", as people may not be familiar with `$,` and `$\`; you've got to decide that for yourself. hdp. p.s. tilly's idea is better than mine.	[reply] [d/l] [select]
Re: map vs. foreach by Albannach (Monsignor) on Apr 25, 2001 at 07:27 UTC
From an efficiency standpoint, I'm lead to believe there is a good reason not to use map in a void context - you're making Perl do a lot of work then you throw it away. -- I'd like to be able to assign to an luser	[reply]
Re: map vs. foreach by jeroenes (Priest) on Apr 25, 2001 at 15:37 UTC
I smell a use for supersplit here. These days it's also available on CPAN: SuperSplit! `use SuperSplit; $pwd = supersplit_open( ':', '/etc/passwd' ); $pwd = [map [@$_[6,7]], @$pwd ]; #Or do you mean 5,6? print superjoin( "\n", $pwd ); #I'd leave the \n out` [download] chipmunk, is this a valid plug ;-)? Jeroen "We are not alone"(FZ)	[reply] [d/l]