diff options
author | Karl Berry <karl@freefriends.org> | 2015-04-26 22:16:26 +0000 |
---|---|---|
committer | Karl Berry <karl@freefriends.org> | 2015-04-26 22:16:26 +0000 |
commit | 342e672574c4e67d510e46ab6acd0e21a7d0cf54 (patch) | |
tree | 79e04202d08c0404bbd780bd26c1e34710e539b6 /Master/tlpkg/tlperl/lib/CORE.pod | |
parent | be2706af7c57a0ef0f4d4e9f684ca4ef74922a82 (diff) |
(tl)perl 5.20.2 for windows, from siep
git-svn-id: svn://tug.org/texlive/trunk@37064 c570f23f-e606-0410-a88d-b1316a301751
Diffstat (limited to 'Master/tlpkg/tlperl/lib/CORE.pod')
-rw-r--r-- | Master/tlpkg/tlperl/lib/CORE.pod | 96 |
1 files changed, 96 insertions, 0 deletions
diff --git a/Master/tlpkg/tlperl/lib/CORE.pod b/Master/tlpkg/tlperl/lib/CORE.pod new file mode 100644 index 00000000000..ce5feb5908a --- /dev/null +++ b/Master/tlpkg/tlperl/lib/CORE.pod @@ -0,0 +1,96 @@ +=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 |