lib/perl5/5.8.8/if.pm

   1 package if;
   2
   3 $VERSION = '0.05';
   4
   5 sub work {
   6   my $method = shift() ? 'import' : 'unimport';
   7   die "Too few arguments to `use if' (some code returning an empty list in list context?)"
   8     unless @_ >= 2;
   9   return unless shift;          # CONDITION
  10
  11   my $p = $_[0];                # PACKAGE
  12   (my $file = "$p.pm") =~ s!::!/!g;
  13   require $file;                # Works even if $_[0] is a keyword (like open)
  14   my $m = $p->can($method);
  15   goto &$m if $m;
  16 }
  17
  18 sub import   { shift; unshift @_, 1; goto &work }
  19 sub unimport { shift; unshift @_, 0; goto &work }
  20
  21 1;
  22 __END__
  23
  24 =head1 NAME
  25
  26 if - C<use> a Perl module if a condition holds
  27
  28 =head1 SYNOPSIS
  29
  30   use if CONDITION, MODULE => ARGUMENTS;
  31
  32 =head1 DESCRIPTION
  33
  34 The construct
  35
  36   use if CONDITION, MODULE => ARGUMENTS;
  37
  38 has no effect unless C<CONDITION> is true.  In this case the effect is
  39 the same as of
  40
  41   use MODULE ARGUMENTS;
  42
  43 Above C<< => >> provides necessary quoting of C<MODULE>.  If not used (e.g.,
  44 no ARGUMENTS to give), you'd better quote C<MODULE> yourselves.
  45
  46 =head1 BUGS
  47
  48 The current implementation does not allow specification of the
  49 required version of the module.
  50
  51 =head1 AUTHOR
  52
  53 Ilya Zakharevich L<mailto:perl-module-if@ilyaz.org>.
  54
  55 =cut
  56