1Package::Stash(3) User Contributed Perl Documentation Package::Stash(3)
2
6 Package::Stash - routines for manipulating stashes
7
9 version 0.38
10
12 my $stash = Package::Stash->new('Foo');
13 $stash->add_symbol('%foo', {bar => 1});
14 # $Foo::foo{bar} == 1
15 $stash->has_symbol('$foo') # false
16 my $namespace = $stash->namespace;
17 *{ $namespace->{foo} }{HASH} # {bar => 1}
18
20 Manipulating stashes (Perl's symbol tables) is occasionally necessary,
21 but incredibly messy, and easy to get wrong. This module hides all of
22 that behind a simple API.
23 NOTE: Most methods in this class require a variable specification that
25 includes a sigil. If this sigil is absent, it is assumed to represent
26 the IO slot.
27 Due to limitations in the typeglob API available to perl code, and to
29 typeglob manipulation in perl being quite slow, this module provides
30 two implementations - one in pure perl, and one using XS. The XS
31 implementation is to be preferred for most usages; the pure perl one is
32 provided for cases where XS modules are not a possibility. The current
33 implementation in use can be set by setting
34 $ENV{PACKAGE_STASH_IMPLEMENTATION} or $Package::Stash::IMPLEMENTATION
35 before loading Package::Stash (with the environment variable taking
36 precedence), otherwise, it will use the XS implementation if possible,
37 falling back to the pure perl one.
38
40 new $package_name
41 Creates a new "Package::Stash" object, for the package given as the
42 only argument.
43 name
45 Returns the name of the package that this object represents.
46 namespace
48 Returns the raw stash itself.
49 add_symbol $variable $value %opts
51 Adds a new package symbol, for the symbol given as $variable, and
52 optionally gives it an initial value of $value. $variable should be the
53 name of variable including the sigil, so
54 Package::Stash->new('Foo')->add_symbol('%foo')
56 will create %Foo::foo.
58 Valid options (all optional) are "filename", "first_line_num", and
60 "last_line_num".
61 $opts{filename}, $opts{first_line_num}, and $opts{last_line_num} can be
63 used to indicate where the symbol should be regarded as having been
64 defined. Currently these values are only used if the symbol is a
65 subroutine ('"&"' sigil) and only if "$^P & 0x10" is true, in which
66 case the special %DB::sub hash is updated to record the values of
67 "filename", "first_line_num", and "last_line_num" for the subroutine.
68 If these are not passed, their values are inferred (as much as
69 possible) from "caller" information.
70 This is especially useful for debuggers and profilers, which use
72 %DB::sub to determine where the source code for a subroutine can be
73 found. See
74 <http://perldoc.perl.org/perldebguts.html#Debugger-Internals> for more
75 information about %DB::sub.
76 remove_glob $name
78 Removes all package variables with the given name, regardless of sigil.
79 has_symbol $variable
81 Returns whether or not the given package variable (including sigil)
82 exists.
83 get_symbol $variable
85 Returns the value of the given package variable (including sigil).
86 get_or_add_symbol $variable
88 Like "get_symbol", except that it will return an empty hashref or
89 arrayref if the variable doesn't exist.
90 remove_symbol $variable
92 Removes the package variable described by $variable (which includes the
93 sigil); other variables with the same name but different sigils will be
94 untouched.
95 list_all_symbols $type_filter
97 Returns a list of package variable names in the package, without
98 sigils. If a "type_filter" is passed, it is used to select package
99 variables of a given type, where valid types are the slots of a
100 typeglob ('SCALAR', 'CODE', 'HASH', etc). Note that if the package
101 contained any "BEGIN" blocks, perl will leave an empty typeglob in the
102 "BEGIN" slot, so this will show up if no filter is used (and similarly
103 for "INIT", "END", etc).
104 get_all_symbols $type_filter
106 Returns a hashref, keyed by the variable names in the package. If
107 $type_filter is passed, the hash will contain every variable of that
108 type in the package as values, otherwise, it will contain the typeglobs
109 corresponding to the variable names (basically, a clone of the stash).
110
112 It is important to note, that when working with scalar variables, the
113 default behavior is to copy values.
114 my $stash = Package::Stash->new('Some::Namespace');
116 my $variable = 1;
117 # $Some::Namespace::name is a copy of $variable
118 $stash->add_symbol('$name', $variable);
119 $variable++
120 # $Some::Namespace::name == 1 , $variable == 2
121 This will likely confuse people who expect it to work the same as
123 typeglob assignment, which simply creates new references to existing
124 variables.
125 my $variable = 1;
127 {
128 no strict 'refs';
129 # assign $Package::Stash::name = $variable
130 *{'Package::Stash::name'} = \$variable;
131 }
132 $variable++ # affects both names
133 If this behaviour is desired when working with Package::Stash, simply
135 pass Package::Stash a scalar ref:
136 my $stash = Package::Stash->new('Some::Namespace');
138 my $variable = 1;
139 # $Some::Namespace::name is now $variable
140 $stash->add_symbol('$name', \$variable);
141 $variable++
142 # $Some::Namespace::name == 2 , $variable == 2
143 This will be what you want as well if you're ever working with Readonly
145 variables:
146 use Readonly;
148 Readonly my $value, 'hello';
149 $stash->add_symbol('$name', \$value); # reference
151 print $Some::Namespace::name; # hello
152 # Tries to modify the read-only 'hello' and dies.
153 $Some::Namespace::name .= " world";
154 $stash->add_symbol('$name', $value); # copy
156 print $Some::Namespace::name; # hello
157 # No problem, modifying a copy, not the original
158 $Some::Namespace::name .= " world";
159
161 · Class::MOP::Package
162 This module is a factoring out of code that used to live here
164
166 You can find this documentation for this module with the perldoc
167 command.
168 perldoc Package::Stash
170 You can also look for information at:
172 · MetaCPAN
174 <https://metacpan.org/release/Package-Stash>
176 · Github
178 <https://github.com/moose/Package-Stash>
180 · RT: CPAN's request tracker
182 <http://rt.cpan.org/NoAuth/Bugs.html?Dist=Package-Stash>
184 · CPAN Ratings
186 <http://cpanratings.perl.org/d/Package-Stash>
188
190 Based on code from Class::MOP::Package, by Stevan Little and the Moose
191 Cabal.
192
194 · Prior to perl 5.10, scalar slots are only considered to exist if
195 they are defined
196 This is due to a shortcoming within perl itself. See "Making
198 References" in perlref point 7 for more information.
199 · GLOB and FORMAT variables are not (yet) accessible through this
201 module.
202 · Also, see the BUGS section for the specific backends
204 (Package::Stash::XS and Package::Stash::PP)
205 Bugs may be submitted through the RT bug tracker
207 <https://rt.cpan.org/Public/Dist/Display.html?Name=Package-Stash> (or
208 bug-Package-Stash@rt.cpan.org <mailto:bug-Package-Stash@rt.cpan.org>).
209
211 Jesse Luehrs <doy@tozt.net>
212
214 · Karen Etheridge <ether@cpan.org>
215 · Carlos Lima <carlos@multi>
217 · Kent Fredric <kentfredric@gmail.com>
219 · Justin Hunter <justin.d.hunter@gmail.com>
221 · Christian Walde <walde.christian@googlemail.com>
223 · Dave Rolsky <autarch@urth.org>
225 · Niko Tyni <ntyni@debian.org>
227 · Renee <reb@perl-services.de>
229 · Tim Bunce <Tim.Bunce@pobox.com>
231
233 This software is copyright (c) 2018 by Jesse Luehrs.
234 This is free software; you can redistribute it and/or modify it under
236 the same terms as the Perl 5 programming language system itself.
237perl v5.30.1 2020-01-30 Package::Stash(3)