Careful... your advice isn't 100% kosher... if I do exactly what you have listed I get a warning:

Scalar value @array[ eval $splice_str ] better written as $array[ eval $splice_str ] at ./foo.pl line 17.

Which is never really a good thing... we want to stay away from error messages as best as we can :) The best solution then is to wrap the eval in ( ), I wrote up some quick code to benchmark both situations:

#!/usr/bin/perl -w

use vars qw/@splice_array $splice_str @array/;

use strict;
use Benchmark;

my @splice_array    = (2, 3..7);
my $splice_str        = "2, 3..7";
my @array        = (1 .. 10);

sub with_array {
    return @array[@splice_array];
}

sub with_string {
    return @array[ (eval $splice_str) ];
}

timethese (-5, {
        "array"     => \&with_array,
        "string"    => \&with_string,
        });

[download]
and the results... were... well, very within what we would have expected them to be :) 
Benchmark: running array, string, each for at least 5 CPU seconds...
     array:  0 wallclock secs ( 5.02 usr +  0.00 sys =  5.02 CPU) @ 54
+8512.95/s (n=2753535)
    string:  6 wallclock secs ( 5.29 usr +  0.00 sys =  5.29 CPU) @ 56
+98.87/s (n=30147)

[download]
so, the array slice version is only a factor of 100 faster :)

In reply to RE: RE: Splicing an array. by eduardo
in thread Splicing an array. by Anonymous Monk

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