Symbol - phpMan

NAME
    Symbol - manipulate Perl symbols and their names

SYNOPSIS
        use Symbol;

        $sym = gensym;
        open($sym, '<', "filename");
        $_ = <$sym>;
        # etc.

        ungensym $sym;      # no effect

        # replace *FOO{IO} handle but not $FOO, %FOO, etc.
        *FOO = geniosym;

        print qualify("x"), "\n";              # "main::x"
        print qualify("x", "FOO"), "\n";       # "FOO::x"
        print qualify("BAR::x"), "\n";         # "BAR::x"
        print qualify("BAR::x", "FOO"), "\n";  # "BAR::x"
        print qualify("STDOUT", "FOO"), "\n";  # "main::STDOUT" (global)
        print qualify(\*x), "\n";              # returns \*x
        print qualify(\*x, "FOO"), "\n";       # returns \*x

        use strict refs;
        print { qualify_to_ref $fh } "foo!\n";
        $ref = qualify_to_ref $name, $pkg;

        use Symbol qw(delete_package);
        delete_package('Foo::Bar');
        print "deleted\n" unless exists $Foo::{'Bar::'};

DESCRIPTION
    "Symbol::gensym" creates an anonymous glob and returns a reference to
    it. Such a glob reference can be used as a file or directory handle.

    For backward compatibility with older implementations that didn't
    support anonymous globs, "Symbol::ungensym" is also provided. But it
    doesn't do anything.

    "Symbol::geniosym" creates an anonymous IO handle. This can be assigned
    into an existing glob without affecting the non-IO portions of the glob.

    "Symbol::qualify" turns unqualified symbol names into qualified variable
    names (e.g. "myvar" -> "MyPackage::myvar"). If it is given a second
    parameter, "qualify" uses it as the default package; otherwise, it uses
    the package of its caller. Regardless, global variable names (e.g.
    "STDOUT", "ENV", "SIG") are always qualified with "main::".

    Qualification applies only to symbol names (strings). References are
    left unchanged under the assumption that they are glob references, which
    are qualified by their nature.

    "Symbol::qualify_to_ref" is just like "Symbol::qualify" except that it
    returns a glob ref rather than a symbol name, so you can use the result
    even if "use strict 'refs'" is in effect.

    "Symbol::delete_package" wipes out a whole package namespace. Note this
    routine is not exported by default--you may want to import it
    explicitly.

BUGS
    "Symbol::delete_package" is a bit too powerful. It undefines every
    symbol that lives in the specified package. Since perl, for performance
    reasons, does not perform a symbol table lookup each time a function is
    called or a global variable is accessed, some code that has already been
    loaded and that makes use of symbols in package "Foo" may stop working
    after you delete "Foo", even if you reload the "Foo" module afterwards.