Symbol3perl

Usage

    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::'};

Overview

"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.