LPM: Subroutine references, or something ...

[grdodson at lexmark.com]

  The syntax:

    ($foo, $bar) = &{$routine}(@args);

is what is called an "symbolic reference" and used to be the only way to do 
references (perl 4).  The downside is that it is slow and can be a 
sign that you have a bug (maybe you didn't want a reference in the first place).

  The way around this that is OK with "strict refs" is to use
a "hard" reference.  For example if I store a bunch of subs in a hash and 
then call the sub I want based on a hash key:



use strict;

my %subhash = ( sub1 => sub { my $a = shift; print "Sub1 $a\n" },
                sub2 => sub { my $a = shift; print "Sub2 $a\n" },
                sub3 => sub { my $a = shift; print "Sub3 $a\n" },
               );
  

  &{$subhash{sub1}}("arg1");
  &{$subhash{sub2}}("arg22");
  &{$subhash{sub3}}("arg333");

my $s = "sub2"

  &{$subhash{$s}}("args");
exit;

Produces the following output 

Sub1 arg1
Sub2 arg22
Sub3 arg333
Sub2 args


  Hope that helps.  Check out the "Blue Cammel" page 254.


     Thanks.

Graydon Dodson                                    grdodson at lexmark.com
Lexmark International Inc.

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