Pulling out an element from a function return without using an intermediate list

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

Brethren,

How do I pull out the n'th value when a function returns a list, without using an intermediate array variable? E.g. the following works, but by introducing the clutter of @temp;

use strict;

sub dirs{qw(NORTH SOUTH EAST WEST)}
my(@temp) = dirs();
my($horaceGreeleyDir) = $temp[3];
[download]

but the following attempts don't

my($horaceGreeleyDir) = dirs()[3];
my($horaceGreeleyDir) = @{dirs()}[3];
my($horaceGreeleyDir) = ${dirs()}[3];
my($horaceGreeleyDir) =()[3] = dirs();
[download]

This works, but is looks worse than the original:

(undef, undef, undef, my  $horaceGreeleyDir) = dirs();
[download]

Suggestions?

throop

meta-question: on what should I have searched to answer this question myself?

Comment on Pulling out an element from a function return without using an intermediate list Select or Download Code

Replies are listed 'Best First'.
Re: Pulling out an element from a function return without using an intermediate list by ikegami (Patriarch) on Feb 19, 2007 at 21:42 UTC
You want a list slice. `(...)[...]` [download] so `(dirs())[3]` [download]	[reply] [d/l] [select]
Re: Pulling out an element from a function return without using an intermediate list by rhesa (Vicar) on Feb 19, 2007 at 21:42 UTC
`my $horaceGreeleyDir = ( dirs() )[3];` [download]	[reply] [d/l]
Re: Pulling out an element from a function return without using an intermediate list by Joost (Canon) on Feb 19, 2007 at 21:43 UTC
I always do `my (undef, $param, undef, $other, @stuff) = thingy();` [download] Doesn't seem very ugly to me. At least not as ugly as the other options. Your taste may vary :-) "What should it profit a man, if he should win a flame war, yet lose his cool?"	[reply] [d/l]
Re^2: Pulling out an element from a function return without using an intermediate list by throop (Chaplain) on Feb 19, 2007 at 22:11 UTC
Really? `use strict; my(undef, $aa, $bb) = dir(); Can't declare undef operator in my at (eval 159) line 2, near ") ="` [download]	[reply] [d/l]
Re^3: Pulling out an element from a function return without using an intermediate list by GrandFather (Saint) on Feb 19, 2007 at 22:16 UTC
`use strict; use warnings; my (undef, $param, undef, $other, @stuff) = dir(); print "undef, $param, undef, $other, @stuff"; sub dir { return (1, 2, 3, 4, 5, 6); }` [download] Prints: `undef, 2, undef, 4, 5 6` [download] Works fine for me. What version of Perl are you using? DWIM is Perl's answer to Gödel	[reply] [d/l] [select]
Re^3: Pulling out an element from a function return without using an intermediate list by ikegami (Patriarch) on Feb 19, 2007 at 22:17 UTC
On the other hand, the following versions all work: `my $aa; my $bb; (undef, $aa, $bb) = dir();` [download] `my ($aa, $bb); (undef, $aa, $bb) = dir();` [download] `(undef, my $aa, my $bb) = dir();` [download] `(undef, my ($aa, $bb)) = dir();` [download] `my ($aa, $bb) = ( dir() )[1, 2];` [download] Update: Apparently, so does the following (contrary to the parent's claims): `my (undef, $aa, $bb) = dir();` [download] Tested the last one on Perl 5.6.0, 5.6.1, 5.8.0 and 5.8.8.	[reply] [d/l] [select]
Re^3: Pulling out an element from a function return without using an intermediate list by Joost (Canon) on Feb 19, 2007 at 22:36 UTC
Yes, that only works in fairly recent perls.(IIRC it's mentioned in programming perl 3, so that would probably make it 5.6.1 onwards) "What should it profit a man, if he should win a flame war, yet lose his cool?"	[reply]