/usr/share/perl/5.18.2/Symbol.pod is in perl-doc 5.18.2-2ubuntu1.7.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 | =head1 NAME
Symbol - manipulate Perl symbols and their names
=head1 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::'};
=head1 DESCRIPTION
C<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, C<Symbol::ungensym> is also provided.
But it doesn't do anything.
C<Symbol::geniosym> creates an anonymous IO handle. This can be
assigned into an existing glob without affecting the non-IO portions
of the glob.
C<Symbol::qualify> turns unqualified symbol names into qualified
variable names (e.g. "myvar" -E<gt> "MyPackage::myvar"). If it is given a
second parameter, C<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.
C<Symbol::qualify_to_ref> is just like C<Symbol::qualify> except that it
returns a glob ref rather than a symbol name, so you can use the result
even if C<use strict 'refs'> is in effect.
C<Symbol::delete_package> wipes out a whole package namespace. Note
this routine is not exported by default--you may want to import it
explicitly.
=head1 BUGS
C<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 C<Foo> may stop working after you delete C<Foo>, even if
you reload the C<Foo> module afterwards.
=cut
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