Package::Stash(3) User Contributed Perl Documentation Package::Stash(3)
NAME
Package::Stash - routines for manipulating stashes
VERSION
version 0.36
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
new $package_name
Creates a new "Package::Stash" object, for the package given as the only argument.
name
Returns the name of the package that this object represents.
namespace
Returns the raw stash itself.
add_symbol $variable $value %opts
Adds a new package symbol, for the symbol given as $variable, and optionally gives it an initial value of $value. $variable should be the
name of variable including the sigil, so
Package::Stash->new('Foo')->add_symbol('%foo')
will create %Foo::foo.
Valid options (all optional) are "filename", "first_line_num", and "last_line_num".
$opts{filename}, $opts{first_line_num}, and $opts{last_line_num} can be used to indicate where the symbol should be regarded as having been
defined. Currently these values are only used if the symbol is a subroutine ('"&"' sigil) and only if "$^P & 0x10" is true, in which case
the special %DB::sub hash is updated to record the values of "filename", "first_line_num", and "last_line_num" for the subroutine. If these
are not passed, their values are inferred (as much as possible) from "caller" information.
This is especially useful for debuggers and profilers, which use %DB::sub to determine where the source code for a subroutine can be found.
See <http://perldoc.perl.org/perldebguts.html#Debugger-Internals> for more information about %DB::sub.
remove_glob $name
Removes all package variables with the given name, regardless of sigil.
has_symbol $variable
Returns whether or not the given package variable (including sigil) exists.
get_symbol $variable
Returns the value of the given package variable (including sigil).
get_or_add_symbol $variable
Like "get_symbol", except that it will return an empty hashref or arrayref if the variable doesn't exist.
remove_symbol $variable
Removes the package variable described by $variable (which includes the sigil); other variables with the same name but different sigils
will be untouched.
list_all_symbols $type_filter
Returns a list of package variable names in the package, without sigils. If a "type_filter" is passed, it is used to select package
variables of a given type, where valid types are the slots of a typeglob ('SCALAR', 'CODE', 'HASH', etc). Note that if the package
contained any "BEGIN" blocks, perl will leave an empty typeglob in the "BEGIN" slot, so this will show up if no filter is used (and
similarly for "INIT", "END", etc).
get_all_symbols $type_filter
Returns a hashref, keyed by the variable names in the package. If $type_filter is passed, the hash will contain every variable of that type
in the package as values, otherwise, it will contain the typeglobs corresponding to the variable names (basically, a clone of the stash).
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";
BUGS
/ CAVEATS
o 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.
o GLOB and FORMAT variables are not (yet) accessible through this module.
o Also, see the BUGS section for the specific backends (Package::Stash::XS and Package::Stash::PP)
Please report any bugs through RT: email "bug-package-stash at rt.cpan.org", or browse to
<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Package-Stash>.
SEE ALSO
o Class::MOP::Package
This module is a factoring out of code that used to live here
SUPPORT
You can find this documentation for this module with the perldoc command.
perldoc Package::Stash
You can also look for information at:
o MetaCPAN
<https://metacpan.org/release/Package-Stash>
o Github
<https://github.com/doy/package-stash>
o RT: CPAN's request tracker
<http://rt.cpan.org/NoAuth/Bugs.html?Dist=Package-Stash>
o CPAN Ratings
<http://cpanratings.perl.org/d/Package-Stash>
HISTORY
Based on code from Class::MOP::Package, by Stevan Little and the Moose Cabal.
AUTHOR
Jesse Luehrs <doy@tozt.net>
COPYRIGHT AND LICENSE
This software is copyright (c) 2013 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.
perl v5.18.2 2013-09-03 Package::Stash(3)