NAME¶

Package::Stash - Routines for manipulating stashes

VERSION¶

version 0.39

SYNOPSIS¶

  my $stash = Package::Stash->new('Foo');
  $stash->add_symbol('%foo', {bar => 1});
  # $Foo::foo{bar} == 1
  $stash->has_symbol('$foo') # false
  my $namespace = $stash->namespace;
  *{ $namespace->{foo} }{HASH} # {bar => 1}

DESCRIPTION¶

Manipulating stashes (Perl's symbol tables) is occasionally necessary, but incredibly messy, and easy to get wrong. This module hides all of that behind a simple API.

NOTE: Most methods in this class require a variable specification that includes a sigil. If this sigil is absent, it is assumed to represent the IO slot.

Due to limitations in the typeglob API available to perl code, and to typeglob manipulation in perl being quite slow, this module provides two implementations - one in pure perl, and one using XS. The XS implementation is to be preferred for most usages; the pure perl one is provided for cases where XS modules are not a possibility. The current implementation in use can be set by setting $ENV{PACKAGE_STASH_IMPLEMENTATION} or $Package::Stash::IMPLEMENTATION before loading Package::Stash (with the environment variable taking precedence), otherwise, it will use the XS implementation if possible, falling back to the pure perl one.

METHODS¶

  Package::Stash->new('Foo')->add_symbol('%foo')

WORKING WITH VARIABLES¶

It is important to note, that when working with scalar variables, the default behavior is to copy values.

  my $stash = Package::Stash->new('Some::Namespace');
  my $variable = 1;
  # $Some::Namespace::name is a copy of $variable
  $stash->add_symbol('$name', $variable);
  $variable++
  # $Some::Namespace::name == 1 , $variable == 2

This will likely confuse people who expect it to work the same as typeglob assignment, which simply creates new references to existing variables.

  my $variable = 1;
  {
      no strict 'refs';
      # assign $Package::Stash::name = $variable
      *{'Package::Stash::name'} = \$variable;
  }
  $variable++ # affects both names

If this behaviour is desired when working with Package::Stash, simply pass Package::Stash a scalar ref:

  my $stash = Package::Stash->new('Some::Namespace');
  my $variable = 1;
  # $Some::Namespace::name is now $variable
  $stash->add_symbol('$name', \$variable);
  $variable++
  # $Some::Namespace::name == 2 , $variable == 2

This will be what you want as well if you're ever working with Readonly variables:

  use Readonly;
  Readonly my $value, 'hello';
  $stash->add_symbol('$name', \$value); # reference
  print $Some::Namespace::name; # hello
  # Tries to modify the read-only 'hello' and dies.
  $Some::Namespace::name .= " world";
  $stash->add_symbol('$name', $value); # copy
  print $Some::Namespace::name; # hello
  # No problem, modifying a copy, not the original
  $Some::Namespace::name .= " world";

SEE ALSO¶

•

Class::MOP::Package

This module is a factoring out of code that used to live here

HISTORY¶

Based on code from Class::MOP::Package, by Stevan Little and the Moose Cabal.

BUGS / CAVEATS¶

• Prior to perl 5.10, scalar slots are only considered to exist if they are defined

  This is due to a shortcoming within perl itself. See "Making References" in perlref point 7 for more information.

• GLOB and FORMAT variables are not (yet) accessible through this module.
• Also, see the BUGS section for the specific backends (Package::Stash::XS and Package::Stash::PP)

Bugs may be submitted through the RT bug tracker <https://rt.cpan.org/Public/Dist/Display.html?Name=Package-Stash> (or bug-Package-Stash@rt.cpan.org <mailto:bug-Package-Stash@rt.cpan.org>).

AUTHORS¶

• Stevan Little <stevan.little@iinteractive.com>
• Jesse Luehrs <doy@tozt.net>

CONTRIBUTORS¶

• Karen Etheridge <ether@cpan.org>
• Carlos Lima <carlos@multi>
• Dave Rolsky <autarch@urth.org>
• Justin Hunter <justin.d.hunter@gmail.com>
• Christian Walde <walde.christian@googlemail.com>
• Kent Fredric <kentfredric@gmail.com>
• Niko Tyni <ntyni@debian.org>
• Renee <reb@perl-services.de>
• Tim Bunce <Tim.Bunce@pobox.com>

COPYRIGHT AND LICENSE¶

This software is copyright (c) 2020 by Jesse Luehrs.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.