1 package Package::Stash;
6 use Scalar::Util qw(reftype);
10 Package::Stash - routines for manipulating stashes
14 my $stash = Package::Stash->new('Foo');
15 $stash->add_package_symbol('%foo', {bar => 1});
17 $stash->has_package_symbol('$foo') # false
18 my $namespace = $stash->namespace;
19 *{ $namespace->{foo} }{HASH} # {bar => 1}
23 Manipulating stashes (Perl's symbol tables) is occasionally necessary, but
24 incredibly messy, and easy to get wrong. This module hides all of that behind a
27 NOTE: Most methods in this class require a variable specification that includes
28 a sigil. If this sigil is absent, it is assumed to represent the IO slot.
34 =head2 new $package_name
36 Creates a new C<Package::Stash> object, for the package given as the only
44 return bless { 'package' => $namespace }, $class;
49 Returns the name of the package that this object represents.
54 return $_[0]->{package};
59 Returns the raw stash itself.
65 # because of issues with the Perl API
66 # to the typeglob in some versions, we
67 # need to just always grab a new
68 # reference to the hash here. Ideally
69 # we could just store a ref and it would
70 # Just Work, but oh well :\
72 return \%{$_[0]->name . '::'};
84 sub _deconstruct_variable_name {
85 my ($self, $variable) = @_;
87 (defined $variable && length $variable)
88 || confess "You must pass a variable name";
90 my $sigil = substr($variable, 0, 1, '');
92 if (exists $SIGIL_MAP{$sigil}) {
93 return ($variable, $sigil, $SIGIL_MAP{$sigil});
96 return ("${sigil}${variable}", '', $SIGIL_MAP{''});
101 =head2 add_package_symbol $variable $value
103 Adds a new package symbol, for the symbol given as C<$variable>, and optionally
104 gives it an initial value of C<$value>. C<$variable> should be the name of
105 variable including the sigil, so
107 Package::Stash->new('Foo')->add_package_symbol('%foo')
109 will create C<%Foo::foo>.
113 sub _valid_for_type {
115 my ($value, $type) = @_;
116 if ($type eq 'HASH' || $type eq 'ARRAY'
117 || $type eq 'IO' || $type eq 'CODE') {
118 return reftype($value) eq $type;
121 my $ref = reftype($value);
122 return !defined($ref) || $ref eq 'SCALAR' || $ref eq 'REF' || $ref eq 'LVALUE';
126 sub add_package_symbol {
127 my ($self, $variable, $initial_value) = @_;
129 my ($name, $sigil, $type) = ref $variable eq 'HASH'
130 ? @{$variable}{qw[name sigil type]}
131 : $self->_deconstruct_variable_name($variable);
134 $self->_valid_for_type($initial_value, $type)
135 || confess "$initial_value is not of type $type";
138 my $pkg = $self->name;
141 no warnings 'redefine', 'misc', 'prototype';
142 *{$pkg . '::' . $name} = ref $initial_value ? $initial_value : \$initial_value;
145 =head2 remove_package_glob $name
147 Removes all package variables with the given name, regardless of sigil.
151 sub remove_package_glob {
152 my ($self, $name) = @_;
154 delete ${$self->name . '::'}{$name};
157 # ... these functions deal with stuff on the namespace level
159 =head2 has_package_symbol $variable
161 Returns whether or not the given package variable (including sigil) exists.
165 sub has_package_symbol {
166 my ($self, $variable) = @_;
168 my ($name, $sigil, $type) = ref $variable eq 'HASH'
169 ? @{$variable}{qw[name sigil type]}
170 : $self->_deconstruct_variable_name($variable);
172 my $namespace = $self->namespace;
174 return unless exists $namespace->{$name};
176 my $entry_ref = \$namespace->{$name};
177 if (reftype($entry_ref) eq 'GLOB') {
178 if ( $type eq 'SCALAR' ) {
179 return defined ${ *{$entry_ref}{SCALAR} };
182 return defined *{$entry_ref}{$type};
186 # a symbol table entry can be -1 (stub), string (stub with prototype),
187 # or reference (constant)
188 return $type eq 'CODE';
192 =head2 get_package_symbol $variable
194 Returns the value of the given package variable (including sigil).
198 sub get_package_symbol {
199 my ($self, $variable) = @_;
201 my ($name, $sigil, $type) = ref $variable eq 'HASH'
202 ? @{$variable}{qw[name sigil type]}
203 : $self->_deconstruct_variable_name($variable);
205 my $namespace = $self->namespace;
207 if (!exists $namespace->{$name}) {
208 # assigning to the result of this function like
209 # @{$stash->get_package_symbol('@ISA')} = @new_ISA
210 # makes the result not visible until the variable is explicitly
211 # accessed... in the case of @ISA, this might never happen
212 # for instance, assigning like that and then calling $obj->isa
213 # will fail. see t/005-isa.t
214 if ($type eq 'ARRAY' && $name ne 'ISA') {
215 $self->add_package_symbol($variable, []);
217 elsif ($type eq 'HASH') {
218 $self->add_package_symbol($variable, {});
222 $self->add_package_symbol($variable)
226 my $entry_ref = \$namespace->{$name};
228 if (ref($entry_ref) eq 'GLOB') {
229 return *{$entry_ref}{$type};
232 if ($type eq 'CODE') {
234 return \&{ $self->name . '::' . $name };
242 =head2 remove_package_symbol $variable
244 Removes the package variable described by C<$variable> (which includes the
245 sigil); other variables with the same name but different sigils will be
250 sub remove_package_symbol {
251 my ($self, $variable) = @_;
253 my ($name, $sigil, $type) = ref $variable eq 'HASH'
254 ? @{$variable}{qw[name sigil type]}
255 : $self->_deconstruct_variable_name($variable);
258 # no doubt this is grossly inefficient and
259 # could be done much easier and faster in XS
261 my ($scalar_desc, $array_desc, $hash_desc, $code_desc, $io_desc) = (
262 { sigil => '$', type => 'SCALAR', name => $name },
263 { sigil => '@', type => 'ARRAY', name => $name },
264 { sigil => '%', type => 'HASH', name => $name },
265 { sigil => '&', type => 'CODE', name => $name },
266 { sigil => '', type => 'IO', name => $name },
269 my ($scalar, $array, $hash, $code, $io);
270 if ($type eq 'SCALAR') {
271 $array = $self->get_package_symbol($array_desc) if $self->has_package_symbol($array_desc);
272 $hash = $self->get_package_symbol($hash_desc) if $self->has_package_symbol($hash_desc);
273 $code = $self->get_package_symbol($code_desc) if $self->has_package_symbol($code_desc);
274 $io = $self->get_package_symbol($io_desc) if $self->has_package_symbol($io_desc);
276 elsif ($type eq 'ARRAY') {
277 $scalar = $self->get_package_symbol($scalar_desc);
278 $hash = $self->get_package_symbol($hash_desc) if $self->has_package_symbol($hash_desc);
279 $code = $self->get_package_symbol($code_desc) if $self->has_package_symbol($code_desc);
280 $io = $self->get_package_symbol($io_desc) if $self->has_package_symbol($io_desc);
282 elsif ($type eq 'HASH') {
283 $scalar = $self->get_package_symbol($scalar_desc);
284 $array = $self->get_package_symbol($array_desc) if $self->has_package_symbol($array_desc);
285 $code = $self->get_package_symbol($code_desc) if $self->has_package_symbol($code_desc);
286 $io = $self->get_package_symbol($io_desc) if $self->has_package_symbol($io_desc);
288 elsif ($type eq 'CODE') {
289 $scalar = $self->get_package_symbol($scalar_desc);
290 $array = $self->get_package_symbol($array_desc) if $self->has_package_symbol($array_desc);
291 $hash = $self->get_package_symbol($hash_desc) if $self->has_package_symbol($hash_desc);
292 $io = $self->get_package_symbol($io_desc) if $self->has_package_symbol($io_desc);
294 elsif ($type eq 'IO') {
295 $scalar = $self->get_package_symbol($scalar_desc);
296 $array = $self->get_package_symbol($array_desc) if $self->has_package_symbol($array_desc);
297 $hash = $self->get_package_symbol($hash_desc) if $self->has_package_symbol($hash_desc);
298 $code = $self->get_package_symbol($code_desc) if $self->has_package_symbol($code_desc);
301 confess "This should never ever ever happen";
304 $self->remove_package_glob($name);
306 $self->add_package_symbol($scalar_desc => $scalar);
307 $self->add_package_symbol($array_desc => $array) if defined $array;
308 $self->add_package_symbol($hash_desc => $hash) if defined $hash;
309 $self->add_package_symbol($code_desc => $code) if defined $code;
310 $self->add_package_symbol($io_desc => $io) if defined $io;
313 =head2 list_all_package_symbols $type_filter
315 Returns a list of package variable names in the package, without sigils. If a
316 C<type_filter> is passed, it is used to select package variables of a given
317 type, where valid types are the slots of a typeglob ('SCALAR', 'CODE', 'HASH',
322 sub list_all_package_symbols {
323 my ($self, $type_filter) = @_;
325 my $namespace = $self->namespace;
326 return keys %{$namespace} unless defined $type_filter;
329 # or we can filter based on
330 # type (SCALAR|ARRAY|HASH|CODE)
331 if ($type_filter eq 'CODE') {
333 (ref($namespace->{$_})
334 ? (ref($namespace->{$_}) eq 'SCALAR')
335 : (ref(\$namespace->{$_}) eq 'GLOB'
336 && defined(*{$namespace->{$_}}{CODE})));
337 } keys %{$namespace};
339 return grep { *{$namespace->{$_}}{$type_filter} } keys %{$namespace};
347 Please report any bugs through RT: email
348 C<bug-package-stash at rt.cpan.org>, or browse to
349 L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Package-Stash>.
353 L<Class::MOP::Package> - this module is a factoring out of code that used to
358 You can find this documentation for this module with the perldoc command.
360 perldoc Package::Stash
362 You can also look for information at:
366 =item * AnnoCPAN: Annotated CPAN documentation
368 L<http://annocpan.org/dist/Package-Stash>
372 L<http://cpanratings.perl.org/d/Package-Stash>
374 =item * RT: CPAN's request tracker
376 L<http://rt.cpan.org/NoAuth/Bugs.html?Dist=Package-Stash>
380 L<http://search.cpan.org/dist/Package-Stash>
386 Jesse Luehrs <doy at tozt dot net>
388 Mostly copied from code from L<Class::MOP::Package>, by Stevan Little and the
391 =head1 COPYRIGHT AND LICENSE
393 This software is copyright (c) 2010 by Jesse Luehrs.
395 This is free software; you can redistribute it and/or modify it under
396 the same terms as perl itself.