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authorSiep Kroonenberg <siepo@cybercomm.nl>2011-02-17 16:52:23 +0000
committerSiep Kroonenberg <siepo@cybercomm.nl>2011-02-17 16:52:23 +0000
commit8da2d23733595367fad869e5fbc6c9a87041879b (patch)
tree0f3719f4eea97f872b6347c6d9ff5aa2ccd38299 /Master/tlpkg/tlperl/lib/if.pm
parent9d55a4cf517a832c74e85179eac4239f9be8d2e7 (diff)
New tlperl part VIII
git-svn-id: svn://tug.org/texlive/trunk@21430 c570f23f-e606-0410-a88d-b1316a301751
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diff --git a/Master/tlpkg/tlperl/lib/if.pm b/Master/tlpkg/tlperl/lib/if.pm
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+package if;
+
+$VERSION = '0.05';
+
+sub work {
+ my $method = shift() ? 'import' : 'unimport';
+ die "Too few arguments to `use if' (some code returning an empty list in list context?)"
+ unless @_ >= 2;
+ return unless shift; # CONDITION
+
+ my $p = $_[0]; # PACKAGE
+ (my $file = "$p.pm") =~ s!::!/!g;
+ require $file; # Works even if $_[0] is a keyword (like open)
+ my $m = $p->can($method);
+ goto &$m if $m;
+}
+
+sub import { shift; unshift @_, 1; goto &work }
+sub unimport { shift; unshift @_, 0; goto &work }
+
+1;
+__END__
+
+=head1 NAME
+
+if - C<use> a Perl module if a condition holds
+
+=head1 SYNOPSIS
+
+ use if CONDITION, MODULE => ARGUMENTS;
+
+=head1 DESCRIPTION
+
+The construct
+
+ use if CONDITION, MODULE => ARGUMENTS;
+
+has no effect unless C<CONDITION> is true. In this case the effect is
+the same as of
+
+ use MODULE ARGUMENTS;
+
+Above C<< => >> provides necessary quoting of C<MODULE>. If not used (e.g.,
+no ARGUMENTS to give), you'd better quote C<MODULE> yourselves.
+
+=head1 BUGS
+
+The current implementation does not allow specification of the
+required version of the module.
+
+=head1 AUTHOR
+
+Ilya Zakharevich L<mailto:perl-module-if@ilyaz.org>.
+
+=cut
+