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 $filename $firstlinenum $lastlinenum
103 Adds a new package symbol, for the symbol given as C<$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>.
111 The optional $filename, $firstlinenum, and $lastlinenum arguments can be used
112 to indicate where the symbol should be regarded as having been defined.
113 Currently these values are only used if the symbol is a subroutine ('C<&>'
114 sigil) and only if C<$^P & 0x10> is true. In which case the special
115 C<%DB::sub> hash is updated to record the values of $filename, $firstlinenum,
116 and $lastlinenum for the subroutine.
118 This is especially useful for debuggers and profilers, which use C<%DB::sub> to
119 determine where the source code for a subroutine can be found. See
120 L<http://perldoc.perl.org/perldebguts.html#Debugger-Internals> for more
121 information about C<%DB::sub>.
125 sub _valid_for_type {
127 my ($value, $type) = @_;
128 if ($type eq 'HASH' || $type eq 'ARRAY'
129 || $type eq 'IO' || $type eq 'CODE') {
130 return reftype($value) eq $type;
133 my $ref = reftype($value);
134 return !defined($ref) || $ref eq 'SCALAR' || $ref eq 'REF' || $ref eq 'LVALUE';
138 sub add_package_symbol {
139 my ($self, $variable, $initial_value, %opts) = @_;
141 my ($name, $sigil, $type) = ref $variable eq 'HASH'
142 ? @{$variable}{qw[name sigil type]}
143 : $self->_deconstruct_variable_name($variable);
145 my $pkg = $self->name;
148 $self->_valid_for_type($initial_value, $type)
149 || confess "$initial_value is not of type $type";
151 # cheap fail-fast check for PERLDBf_SUBLINE and '&'
152 if ($^P and $^P & 0x10 && $sigil eq '&') {
153 my $filename = $opts{filename};
154 my $first_line_num = $opts{first_line_num};
156 (undef, $filename, $first_line_num) = caller
157 if not defined $filename;
159 my $last_line_num = $opts{last_line_num} || ($first_line_num ||= 0);
161 # http://perldoc.perl.org/perldebguts.html#Debugger-Internals
162 $DB::sub{$pkg . '::' . $name} = "$filename:$first_line_num-$last_line_num";
167 no warnings 'redefine', 'misc', 'prototype';
168 *{$pkg . '::' . $name} = ref $initial_value ? $initial_value : \$initial_value;
171 =head2 remove_package_glob $name
173 Removes all package variables with the given name, regardless of sigil.
177 sub remove_package_glob {
178 my ($self, $name) = @_;
180 delete ${$self->name . '::'}{$name};
183 # ... these functions deal with stuff on the namespace level
185 =head2 has_package_symbol $variable
187 Returns whether or not the given package variable (including sigil) exists.
191 sub has_package_symbol {
192 my ($self, $variable) = @_;
194 my ($name, $sigil, $type) = ref $variable eq 'HASH'
195 ? @{$variable}{qw[name sigil type]}
196 : $self->_deconstruct_variable_name($variable);
198 my $namespace = $self->namespace;
200 return unless exists $namespace->{$name};
202 my $entry_ref = \$namespace->{$name};
203 if (reftype($entry_ref) eq 'GLOB') {
204 if ( $type eq 'SCALAR' ) {
205 return defined ${ *{$entry_ref}{SCALAR} };
208 return defined *{$entry_ref}{$type};
212 # a symbol table entry can be -1 (stub), string (stub with prototype),
213 # or reference (constant)
214 return $type eq 'CODE';
218 =head2 get_package_symbol $variable
220 Returns the value of the given package variable (including sigil).
224 sub get_package_symbol {
225 my ($self, $variable) = @_;
227 my ($name, $sigil, $type) = ref $variable eq 'HASH'
228 ? @{$variable}{qw[name sigil type]}
229 : $self->_deconstruct_variable_name($variable);
231 my $namespace = $self->namespace;
233 if (!exists $namespace->{$name}) {
234 # assigning to the result of this function like
235 # @{$stash->get_package_symbol('@ISA')} = @new_ISA
236 # makes the result not visible until the variable is explicitly
237 # accessed... in the case of @ISA, this might never happen
238 # for instance, assigning like that and then calling $obj->isa
239 # will fail. see t/005-isa.t
240 if ($type eq 'ARRAY' && $name ne 'ISA') {
241 $self->add_package_symbol($variable, []);
243 elsif ($type eq 'HASH') {
244 $self->add_package_symbol($variable, {});
248 $self->add_package_symbol($variable)
252 my $entry_ref = \$namespace->{$name};
254 if (ref($entry_ref) eq 'GLOB') {
255 return *{$entry_ref}{$type};
258 if ($type eq 'CODE') {
260 return \&{ $self->name . '::' . $name };
268 =head2 remove_package_symbol $variable
270 Removes the package variable described by C<$variable> (which includes the
271 sigil); other variables with the same name but different sigils will be
276 sub remove_package_symbol {
277 my ($self, $variable) = @_;
279 my ($name, $sigil, $type) = ref $variable eq 'HASH'
280 ? @{$variable}{qw[name sigil type]}
281 : $self->_deconstruct_variable_name($variable);
284 # no doubt this is grossly inefficient and
285 # could be done much easier and faster in XS
287 my ($scalar_desc, $array_desc, $hash_desc, $code_desc, $io_desc) = (
288 { sigil => '$', type => 'SCALAR', name => $name },
289 { sigil => '@', type => 'ARRAY', name => $name },
290 { sigil => '%', type => 'HASH', name => $name },
291 { sigil => '&', type => 'CODE', name => $name },
292 { sigil => '', type => 'IO', name => $name },
295 my ($scalar, $array, $hash, $code, $io);
296 if ($type eq 'SCALAR') {
297 $array = $self->get_package_symbol($array_desc) if $self->has_package_symbol($array_desc);
298 $hash = $self->get_package_symbol($hash_desc) if $self->has_package_symbol($hash_desc);
299 $code = $self->get_package_symbol($code_desc) if $self->has_package_symbol($code_desc);
300 $io = $self->get_package_symbol($io_desc) if $self->has_package_symbol($io_desc);
302 elsif ($type eq 'ARRAY') {
303 $scalar = $self->get_package_symbol($scalar_desc);
304 $hash = $self->get_package_symbol($hash_desc) if $self->has_package_symbol($hash_desc);
305 $code = $self->get_package_symbol($code_desc) if $self->has_package_symbol($code_desc);
306 $io = $self->get_package_symbol($io_desc) if $self->has_package_symbol($io_desc);
308 elsif ($type eq 'HASH') {
309 $scalar = $self->get_package_symbol($scalar_desc);
310 $array = $self->get_package_symbol($array_desc) if $self->has_package_symbol($array_desc);
311 $code = $self->get_package_symbol($code_desc) if $self->has_package_symbol($code_desc);
312 $io = $self->get_package_symbol($io_desc) if $self->has_package_symbol($io_desc);
314 elsif ($type eq 'CODE') {
315 $scalar = $self->get_package_symbol($scalar_desc);
316 $array = $self->get_package_symbol($array_desc) if $self->has_package_symbol($array_desc);
317 $hash = $self->get_package_symbol($hash_desc) if $self->has_package_symbol($hash_desc);
318 $io = $self->get_package_symbol($io_desc) if $self->has_package_symbol($io_desc);
320 elsif ($type eq 'IO') {
321 $scalar = $self->get_package_symbol($scalar_desc);
322 $array = $self->get_package_symbol($array_desc) if $self->has_package_symbol($array_desc);
323 $hash = $self->get_package_symbol($hash_desc) if $self->has_package_symbol($hash_desc);
324 $code = $self->get_package_symbol($code_desc) if $self->has_package_symbol($code_desc);
327 confess "This should never ever ever happen";
330 $self->remove_package_glob($name);
332 $self->add_package_symbol($scalar_desc => $scalar);
333 $self->add_package_symbol($array_desc => $array) if defined $array;
334 $self->add_package_symbol($hash_desc => $hash) if defined $hash;
335 $self->add_package_symbol($code_desc => $code) if defined $code;
336 $self->add_package_symbol($io_desc => $io) if defined $io;
339 =head2 list_all_package_symbols $type_filter
341 Returns a list of package variable names in the package, without sigils. If a
342 C<type_filter> is passed, it is used to select package variables of a given
343 type, where valid types are the slots of a typeglob ('SCALAR', 'CODE', 'HASH',
348 sub list_all_package_symbols {
349 my ($self, $type_filter) = @_;
351 my $namespace = $self->namespace;
352 return keys %{$namespace} unless defined $type_filter;
355 # or we can filter based on
356 # type (SCALAR|ARRAY|HASH|CODE)
357 if ($type_filter eq 'CODE') {
359 (ref($namespace->{$_})
360 ? (ref($namespace->{$_}) eq 'SCALAR')
361 : (ref(\$namespace->{$_}) eq 'GLOB'
362 && defined(*{$namespace->{$_}}{CODE})));
363 } keys %{$namespace};
365 return grep { *{$namespace->{$_}}{$type_filter} } keys %{$namespace};
373 Please report any bugs through RT: email
374 C<bug-package-stash at rt.cpan.org>, or browse to
375 L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Package-Stash>.
379 L<Class::MOP::Package> - this module is a factoring out of code that used to
384 You can find this documentation for this module with the perldoc command.
386 perldoc Package::Stash
388 You can also look for information at:
392 =item * AnnoCPAN: Annotated CPAN documentation
394 L<http://annocpan.org/dist/Package-Stash>
398 L<http://cpanratings.perl.org/d/Package-Stash>
400 =item * RT: CPAN's request tracker
402 L<http://rt.cpan.org/NoAuth/Bugs.html?Dist=Package-Stash>
406 L<http://search.cpan.org/dist/Package-Stash>
412 Jesse Luehrs <doy at tozt dot net>
414 Mostly copied from code from L<Class::MOP::Package>, by Stevan Little and the
417 =head1 COPYRIGHT AND LICENSE
419 This software is copyright (c) 2010 by Jesse Luehrs.
421 This is free software; you can redistribute it and/or modify it under
422 the same terms as perl itself.