CORE - phpMan

NAME
    CORE - Namespace for Perl's core routines

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

DESCRIPTION
    The "CORE" namespace gives access to the original built-in functions of
    Perl. The "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 perlfunc.

    For all Perl keywords, a "CORE::" prefix will force the built-in
    function to be used, even if it has been overridden or would normally
    require the 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 (&foo) or call them through references. See
    the "shove" example above. These subroutines exist for all keywords
    except the following:

    "__DATA__", "__END__", "and", "cmp", "default", "do", "dump", "else",
    "elsif", "eq", "eval", "for", "foreach", "format", "ge", "given",
    "goto", "grep", "gt", "if", "last", "le", "local", "lt", "m", "map",
    "my", "ne", "next", "no", "or", "our", "package", "print", "printf",
    "q", "qq", "qr", "qw", "qx", "redo", "require", "return", "s", "say",
    "sort", "state", "sub", "tr", "unless", "until", "use", "when", "while",
    "x", "xor", "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., "eof" vs "eof()"):

    "chdir", "chomp", "chop", "defined", "delete", "eof", "exec", "exists",
    "lstat", "split", "stat", "system", "truncate", "unlink"

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
    "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 "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 "CORE::" prefix:

        print CORE::hex("0x50"),"\n";               # prints 80

AUTHOR
    This documentation provided by Tels <nospam-abuse AT bloodgate.com> 2007.

SEE ALSO
    perlsub, perlfunc.