502 lines
14 KiB
Perl
502 lines
14 KiB
Perl
package Package::Stash::PP;
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use strict;
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use warnings;
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# ABSTRACT: Pure perl implementation of the Package::Stash API
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our $VERSION = '0.39';
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use B;
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use Carp qw(confess);
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use Scalar::Util qw(blessed reftype weaken);
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use Symbol;
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# before 5.12, assigning to the ISA glob would make it lose its magical ->isa
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# powers
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use constant BROKEN_ISA_ASSIGNMENT => ($] < 5.012);
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# before 5.10, stashes don't ever seem to drop to a refcount of zero, so
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# weakening them isn't helpful
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use constant BROKEN_WEAK_STASH => ($] < 5.010);
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# before 5.10, the scalar slot was always treated as existing if the
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# glob existed
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use constant BROKEN_SCALAR_INITIALIZATION => ($] < 5.010);
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# add_method on anon stashes triggers rt.perl #1804 otherwise
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# fixed in perl commit v5.13.3-70-g0fe688f
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use constant BROKEN_GLOB_ASSIGNMENT => ($] < 5.013004);
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# pre-5.10, ->isa lookups were cached in the ::ISA::CACHE:: slot
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use constant HAS_ISA_CACHE => ($] < 5.010);
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#pod =head1 SYNOPSIS
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#pod
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#pod use Package::Stash;
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#pod
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#pod =head1 DESCRIPTION
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#pod
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#pod This is a backend for L<Package::Stash> implemented in pure perl, for those without a compiler or who would like to use this inline in scripts.
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#pod
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#pod =cut
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sub new {
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my $class = shift;
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my ($package) = @_;
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if (!defined($package) || (ref($package) && reftype($package) ne 'HASH')) {
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confess "Package::Stash->new must be passed the name of the "
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. "package to access";
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}
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elsif (ref($package) && reftype($package) eq 'HASH') {
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confess "The PP implementation of Package::Stash does not support "
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. "anonymous stashes before perl 5.14"
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if BROKEN_GLOB_ASSIGNMENT;
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return bless {
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'namespace' => $package,
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}, $class;
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}
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elsif ($package =~ /\A[0-9A-Z_a-z]+(?:::[0-9A-Z_a-z]+)*\z/) {
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return bless {
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'package' => $package,
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}, $class;
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}
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else {
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confess "$package is not a module name";
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}
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}
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sub name {
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confess "Can't call name as a class method"
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unless blessed($_[0]);
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confess "Can't get the name of an anonymous package"
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unless defined($_[0]->{package});
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return $_[0]->{package};
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}
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sub namespace {
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confess "Can't call namespace as a class method"
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unless blessed($_[0]);
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if (BROKEN_WEAK_STASH) {
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no strict 'refs';
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return \%{$_[0]->name . '::'};
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}
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else {
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return $_[0]->{namespace} if defined $_[0]->{namespace};
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{
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no strict 'refs';
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$_[0]->{namespace} = \%{$_[0]->name . '::'};
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}
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weaken($_[0]->{namespace});
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return $_[0]->{namespace};
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}
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}
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{
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my %SIGIL_MAP = (
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'$' => 'SCALAR',
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'@' => 'ARRAY',
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'%' => 'HASH',
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'&' => 'CODE',
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'' => 'IO',
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);
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sub _deconstruct_variable_name {
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my ($variable) = @_;
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my @ret;
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if (ref($variable) eq 'HASH') {
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@ret = @{$variable}{qw[name sigil type]};
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}
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else {
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(defined $variable && length $variable)
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|| confess "You must pass a variable name";
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my $sigil = substr($variable, 0, 1, '');
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if (exists $SIGIL_MAP{$sigil}) {
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@ret = ($variable, $sigil, $SIGIL_MAP{$sigil});
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}
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else {
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@ret = ("${sigil}${variable}", '', $SIGIL_MAP{''});
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}
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}
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# XXX in pure perl, this will access things in inner packages,
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# in xs, this will segfault - probably look more into this at
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# some point
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($ret[0] !~ /::/)
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|| confess "Variable names may not contain ::";
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return @ret;
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}
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}
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sub _valid_for_type {
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my ($value, $type) = @_;
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if ($type eq 'HASH' || $type eq 'ARRAY'
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|| $type eq 'IO' || $type eq 'CODE') {
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return reftype($value) eq $type;
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}
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else {
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my $ref = reftype($value);
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return !defined($ref) || $ref eq 'SCALAR' || $ref eq 'REF' || $ref eq 'LVALUE' || $ref eq 'REGEXP' || $ref eq 'VSTRING';
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}
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}
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sub add_symbol {
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my ($self, $variable, $initial_value, %opts) = @_;
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my ($name, $sigil, $type) = _deconstruct_variable_name($variable);
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if (@_ > 2) {
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_valid_for_type($initial_value, $type)
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|| confess "$initial_value is not of type $type";
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# cheap fail-fast check for PERLDBf_SUBLINE and '&'
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if ($^P and $^P & 0x10 && $sigil eq '&') {
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my $filename = $opts{filename};
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my $first_line_num = $opts{first_line_num};
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(undef, $filename, $first_line_num) = caller
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if not defined $filename;
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my $last_line_num = $opts{last_line_num} || ($first_line_num ||= 0);
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# http://perldoc.perl.org/perldebguts.html#Debugger-Internals
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$DB::sub{$self->name . '::' . $name} = "$filename:$first_line_num-$last_line_num";
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}
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}
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if (BROKEN_GLOB_ASSIGNMENT) {
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if (@_ > 2) {
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no strict 'refs';
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no warnings 'redefine';
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*{ $self->name . '::' . $name } = ref $initial_value
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? $initial_value : \$initial_value;
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}
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else {
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no strict 'refs';
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if (BROKEN_ISA_ASSIGNMENT && $name eq 'ISA') {
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*{ $self->name . '::' . $name };
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}
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else {
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my $undef = _undef_ref_for_type($type);
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*{ $self->name . '::' . $name } = $undef;
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}
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}
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}
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else {
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my $namespace = $self->namespace;
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{
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# using glob aliasing instead of Symbol::gensym, because otherwise,
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# magic doesn't get applied properly.
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# see <20120710063744.19360.qmail@lists-nntp.develooper.com> on p5p
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local *__ANON__:: = $namespace;
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no strict 'refs';
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no warnings 'void';
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no warnings 'once';
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*{"__ANON__::$name"};
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}
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if (@_ > 2) {
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no warnings 'redefine';
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*{ $namespace->{$name} } = ref $initial_value
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? $initial_value : \$initial_value;
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}
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else {
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return if BROKEN_ISA_ASSIGNMENT && $name eq 'ISA';
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*{ $namespace->{$name} } = _undef_ref_for_type($type);
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}
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}
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}
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sub _undef_ref_for_type {
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my ($type) = @_;
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if ($type eq 'ARRAY') {
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return [];
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}
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elsif ($type eq 'HASH') {
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return {};
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}
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elsif ($type eq 'SCALAR') {
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return \undef;
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}
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elsif ($type eq 'IO') {
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return Symbol::geniosym;
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}
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elsif ($type eq 'CODE') {
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confess "Don't know how to vivify CODE variables";
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}
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else {
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confess "Unknown type $type in vivication";
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}
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}
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sub remove_glob {
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my ($self, $name) = @_;
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delete $self->namespace->{$name};
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}
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sub has_symbol {
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my ($self, $variable) = @_;
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my ($name, $sigil, $type) = _deconstruct_variable_name($variable);
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my $namespace = $self->namespace;
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return unless exists $namespace->{$name};
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my $entry_ref = \$namespace->{$name};
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if (reftype($entry_ref) eq 'GLOB') {
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if ($type eq 'SCALAR') {
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if (BROKEN_SCALAR_INITIALIZATION) {
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return defined ${ *{$entry_ref}{$type} };
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}
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else {
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my $sv = B::svref_2object($entry_ref)->SV;
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return $sv->isa('B::SV')
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|| ($sv->isa('B::SPECIAL')
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&& $B::specialsv_name[$$sv] ne 'Nullsv');
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}
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}
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else {
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return defined *{$entry_ref}{$type};
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}
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}
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else {
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# a symbol table entry can be -1 (stub), string (stub with prototype),
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# or reference (constant)
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return $type eq 'CODE';
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}
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}
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sub get_symbol {
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my ($self, $variable, %opts) = @_;
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my ($name, $sigil, $type) = _deconstruct_variable_name($variable);
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my $namespace = $self->namespace;
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if (!exists $namespace->{$name}) {
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if ($opts{vivify}) {
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$self->add_symbol($variable);
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}
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else {
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return undef;
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}
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}
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my $entry_ref = \$namespace->{$name};
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if (ref($entry_ref) eq 'GLOB') {
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return *{$entry_ref}{$type};
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}
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else {
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if ($type eq 'CODE') {
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if (BROKEN_GLOB_ASSIGNMENT || defined($self->{package})) {
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no strict 'refs';
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return \&{ $self->name . '::' . $name };
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}
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# XXX we should really be able to support arbitrary anonymous
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# stashes here... (not just via Package::Anon)
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if (blessed($namespace) && $namespace->isa('Package::Anon')) {
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# ->can will call gv_init for us, which inflates the glob
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# don't know how to do this in general
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$namespace->bless(\(my $foo))->can($name);
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}
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else {
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confess "Don't know how to inflate a " . ref($entry_ref)
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. " into a full coderef (perhaps you could use"
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. " Package::Anon instead of a bare stash?)"
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}
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return *{ $namespace->{$name} }{CODE};
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}
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else {
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return undef;
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}
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}
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}
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sub get_or_add_symbol {
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my $self = shift;
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$self->get_symbol(@_, vivify => 1);
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}
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sub remove_symbol {
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my ($self, $variable) = @_;
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my ($name, $sigil, $type) = _deconstruct_variable_name($variable);
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# FIXME:
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# no doubt this is grossly inefficient and
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# could be done much easier and faster in XS
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my %desc = (
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SCALAR => { sigil => '$', type => 'SCALAR', name => $name },
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ARRAY => { sigil => '@', type => 'ARRAY', name => $name },
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HASH => { sigil => '%', type => 'HASH', name => $name },
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CODE => { sigil => '&', type => 'CODE', name => $name },
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IO => { sigil => '', type => 'IO', name => $name },
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);
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confess "This should never ever ever happen" if !$desc{$type};
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my @types_to_store = grep { $type ne $_ && $self->has_symbol($desc{$_}) }
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keys %desc;
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my %values = map { $_, $self->get_symbol($desc{$_}) } @types_to_store;
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$values{SCALAR} = $self->get_symbol($desc{SCALAR})
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if !defined $values{SCALAR}
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&& $type ne 'SCALAR'
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&& BROKEN_SCALAR_INITIALIZATION;
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$self->remove_glob($name);
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$self->add_symbol($desc{$_} => $values{$_})
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for grep { defined $values{$_} } keys %values;
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}
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sub list_all_symbols {
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my ($self, $type_filter) = @_;
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my $namespace = $self->namespace;
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if (HAS_ISA_CACHE) {
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return grep { $_ ne '::ISA::CACHE::' } keys %{$namespace}
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unless defined $type_filter;
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}
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else {
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return keys %{$namespace}
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unless defined $type_filter;
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}
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# NOTE:
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# or we can filter based on
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# type (SCALAR|ARRAY|HASH|CODE)
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if ($type_filter eq 'CODE') {
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return grep {
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# any non-typeglob in the symbol table is a constant or stub
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ref(\$namespace->{$_}) ne 'GLOB'
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# regular subs are stored in the CODE slot of the typeglob
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|| defined(*{$namespace->{$_}}{CODE})
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} keys %{$namespace};
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}
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elsif ($type_filter eq 'SCALAR') {
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return grep {
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!(HAS_ISA_CACHE && $_ eq '::ISA::CACHE::') &&
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(BROKEN_SCALAR_INITIALIZATION
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? (ref(\$namespace->{$_}) eq 'GLOB'
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&& defined(${*{$namespace->{$_}}{'SCALAR'}}))
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: (do {
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my $entry = \$namespace->{$_};
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ref($entry) eq 'GLOB'
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&& B::svref_2object($entry)->SV->isa('B::SV')
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}))
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} keys %{$namespace};
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}
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else {
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return grep {
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ref(\$namespace->{$_}) eq 'GLOB'
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&& defined(*{$namespace->{$_}}{$type_filter})
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} keys %{$namespace};
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}
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}
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sub get_all_symbols {
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my ($self, $type_filter) = @_;
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my $namespace = $self->namespace;
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return { %{$namespace} } unless defined $type_filter;
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return {
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map { $_ => $self->get_symbol({name => $_, type => $type_filter}) }
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$self->list_all_symbols($type_filter)
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}
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}
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__END__
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=pod
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=encoding UTF-8
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=head1 NAME
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Package::Stash::PP - Pure perl implementation of the Package::Stash API
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=head1 VERSION
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version 0.39
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=head1 SYNOPSIS
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use Package::Stash;
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=head1 DESCRIPTION
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This is a backend for L<Package::Stash> implemented in pure perl, for those without a compiler or who would like to use this inline in scripts.
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=for stopwords TODO
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=over 4
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=item * remove_symbol also replaces the associated typeglob
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This can cause unexpected behavior when doing manipulation at compile time -
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removing subroutines will still allow them to be called from within the package
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as subroutines (although they will not be available as methods). This can be
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considered a feature in some cases (this is how L<namespace::clean> works, for
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instance), but should not be relied upon - use C<remove_glob> directly if you
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want this behavior.
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=item * Some minor memory leaks
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The pure perl implementation has a couple minor memory leaks (see the TODO
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tests in t/20-leaks.t) that I'm having a hard time tracking down - these may be
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core perl bugs, it's hard to tell.
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=back
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=head1 SEE ALSO
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=over 4
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=item * L<Class::MOP::Package>
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This module is a factoring out of code that used to live here
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=back
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=for Pod::Coverage BROKEN_ISA_ASSIGNMENT
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add_symbol
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get_all_symbols
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get_or_add_symbol
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get_symbol
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has_symbol
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list_all_symbols
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name
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namespace
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new
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remove_glob
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=head1 BUGS
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Bugs may be submitted through L<the RT bug tracker|https://rt.cpan.org/Public/Dist/Display.html?Name=Package-Stash>
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(or L<bug-Package-Stash@rt.cpan.org|mailto:bug-Package-Stash@rt.cpan.org>).
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=head1 AUTHOR
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Mostly copied from code from L<Class::MOP::Package>, by Stevan Little and the
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Moose Cabal.
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=head1 COPYRIGHT AND LICENSE
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This software is copyright (c) 2020 by Jesse Luehrs.
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This is free software; you can redistribute it and/or modify it under
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the same terms as the Perl 5 programming language system itself.
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=cut
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