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::'};
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.