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authorKarl Berry <karl@freefriends.org>2015-04-26 22:16:26 +0000
committerKarl Berry <karl@freefriends.org>2015-04-26 22:16:26 +0000
commit342e672574c4e67d510e46ab6acd0e21a7d0cf54 (patch)
tree79e04202d08c0404bbd780bd26c1e34710e539b6 /Master/tlpkg/tlperl/lib/CORE.pod
parentbe2706af7c57a0ef0f4d4e9f684ca4ef74922a82 (diff)
(tl)perl 5.20.2 for windows, from siep
git-svn-id: svn://tug.org/texlive/trunk@37064 c570f23f-e606-0410-a88d-b1316a301751
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+=head1 NAME
+
+CORE - Namespace for Perl's core routines
+
+=head1 SYNOPSIS
+
+ BEGIN {
+ *CORE::GLOBAL::hex = sub { 1; };
+ }
+
+ print hex("0x50"),"\n"; # prints 1
+ print CORE::hex("0x50"),"\n"; # prints 80
+ CORE::say "yes"; # prints yes
+
+ BEGIN { *shove = \&CORE::push; }
+ shove @array, 1,2,3; # pushes on to @array
+
+=head1 DESCRIPTION
+
+The C<CORE> namespace gives access to the original built-in functions of
+Perl. The C<CORE> package is built into
+Perl, and therefore you do not need to use or
+require a hypothetical "CORE" module prior to accessing routines in this
+namespace.
+
+A list of the built-in functions in Perl can be found in L<perlfunc>.
+
+For all Perl keywords, a C<CORE::> prefix will force the built-in function
+to be used, even if it has been overridden or would normally require the
+L<feature> pragma. Despite appearances, this has nothing to do with the
+CORE package, but is part of Perl's syntax.
+
+For many Perl functions, the CORE package contains real subroutines. This
+feature is new in Perl 5.16. You can take references to these and make
+aliases. However, some can only be called as barewords; i.e., you cannot
+use ampersand syntax (C<&foo>) or call them through references. See the
+C<shove> example above. These subroutines exist for all keywords except the following:
+
+C<__DATA__>, C<__END__>, C<and>, C<cmp>, C<default>, C<do>, C<dump>,
+C<else>, C<elsif>, C<eq>, C<eval>, C<for>, C<foreach>, C<format>, C<ge>,
+C<given>, C<goto>, C<grep>, C<gt>, C<if>, C<last>, C<le>, C<local>, C<lt>,
+C<m>, C<map>, C<my>, C<ne>, C<next>, C<no>, C<or>, C<our>, C<package>,
+C<print>, C<printf>, C<q>, C<qq>, C<qr>, C<qw>, C<qx>, C<redo>, C<require>,
+C<return>, C<s>, C<say>, C<sort>, C<state>, C<sub>, C<tr>, C<unless>,
+C<until>, C<use>, C<when>, C<while>, C<x>, C<xor>, C<y>
+
+Calling with
+ampersand syntax and through references does not work for the following
+functions, as they have special syntax that cannot always be translated
+into a simple list (e.g., C<eof> vs C<eof()>):
+
+C<chdir>, C<chomp>, C<chop>, C<defined>, C<delete>, C<each>,
+C<eof>, C<exec>, C<exists>, C<keys>, C<lstat>, C<pop>, C<push>,
+C<shift>, C<splice>, C<split>, C<stat>, C<system>, C<truncate>,
+C<unlink>, C<unshift>, C<values>
+
+=head1 OVERRIDING CORE FUNCTIONS
+
+To override a Perl built-in routine with your own version, you need to
+import it at compile-time. This can be conveniently achieved with the
+C<subs> pragma. This will affect only the package in which you've imported
+the said subroutine:
+
+ use subs 'chdir';
+ sub chdir { ... }
+ chdir $somewhere;
+
+To override a built-in globally (that is, in all namespaces), you need to
+import your function into the C<CORE::GLOBAL> pseudo-namespace at compile
+time:
+
+ BEGIN {
+ *CORE::GLOBAL::hex = sub {
+ # ... your code here
+ };
+ }
+
+The new routine will be called whenever a built-in function is called
+without a qualifying package:
+
+ print hex("0x50"),"\n"; # prints 1
+
+In both cases, if you want access to the original, unaltered routine, use
+the C<CORE::> prefix:
+
+ print CORE::hex("0x50"),"\n"; # prints 80
+
+=head1 AUTHOR
+
+This documentation provided by Tels <nospam-abuse@bloodgate.com> 2007.
+
+=head1 SEE ALSO
+
+L<perlsub>, L<perlfunc>.
+
+=cut