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Symbol
manipulate Perl symbols and their names

Symbol - manipulate Perl symbols and their names


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";              # "Test::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.

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