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How do I use a sort routine from a different package/module?

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Contributed by bobf on Jun 09, 2005 at 07:33 UTC
Q&A  > sorting


Answer: How do I use a sort routine from a different package/module?
contributed by bobf

There are (at least) two ways to access sort routines in a different package:

  • Prototype the sort subfunction and pass the values as arguments, which can then be accessed by directly indexing @_
  • Fully qualifying $a and $b in the sort routine with the package name of the caller (this works because prior to Perl 6 the elements to be compared are passed to the sort routine in the package global variables $a and $b)

use strict; use warnings; use my_sort_routines; package myprogram; my @data = ( 4, 2, 1, 3 ); my @sorted_proto = sort my_sort_routines::prototyped @data; my @sorted_qual = sort my_sort_routines::qualify_pkg @data; print @sorted_proto, "\n"; #1234 print @sorted_qual, "\n"; #1234 package my_sort_routines; sub prototyped ($$) { # Access the arguments directly by indexing @_ $_[0] <=> $_[1]; } sub qualify_pkg { # Qualify $a and $b with the name of the calling package # Symbolic refs require "no strict refs" here # Symbol::qualify could simplify this, but this illustrates # how to do it without an additional module my $pkg = caller; no strict 'refs'; ${"${pkg}::a"} <=> ${"${pkg}::b"}; }

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