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Diffstat (limited to 'contrib/perl5/lib/Tie/Hash.pm')
-rw-r--r-- | contrib/perl5/lib/Tie/Hash.pm | 160 |
1 files changed, 0 insertions, 160 deletions
diff --git a/contrib/perl5/lib/Tie/Hash.pm b/contrib/perl5/lib/Tie/Hash.pm deleted file mode 100644 index 2244711..0000000 --- a/contrib/perl5/lib/Tie/Hash.pm +++ /dev/null @@ -1,160 +0,0 @@ -package Tie::Hash; - -=head1 NAME - -Tie::Hash, Tie::StdHash - base class definitions for tied hashes - -=head1 SYNOPSIS - - package NewHash; - require Tie::Hash; - - @ISA = (Tie::Hash); - - sub DELETE { ... } # Provides needed method - sub CLEAR { ... } # Overrides inherited method - - - package NewStdHash; - require Tie::Hash; - - @ISA = (Tie::StdHash); - - # All methods provided by default, define only those needing overrides - sub DELETE { ... } - - - package main; - - tie %new_hash, 'NewHash'; - tie %new_std_hash, 'NewStdHash'; - -=head1 DESCRIPTION - -This module provides some skeletal methods for hash-tying classes. See -L<perltie> for a list of the functions required in order to tie a hash -to a package. The basic B<Tie::Hash> package provides a C<new> method, as well -as methods C<TIEHASH>, C<EXISTS> and C<CLEAR>. The B<Tie::StdHash> package -provides most methods required for hashes in L<perltie>. It inherits from -B<Tie::Hash>, and causes tied hashes to behave exactly like standard hashes, -allowing for selective overloading of methods. The C<new> method is provided -as grandfathering in the case a class forgets to include a C<TIEHASH> method. - -For developers wishing to write their own tied hashes, the required methods -are briefly defined below. See the L<perltie> section for more detailed -descriptive, as well as example code: - -=over - -=item TIEHASH classname, LIST - -The method invoked by the command C<tie %hash, classname>. Associates a new -hash instance with the specified class. C<LIST> would represent additional -arguments (along the lines of L<AnyDBM_File> and compatriots) needed to -complete the association. - -=item STORE this, key, value - -Store datum I<value> into I<key> for the tied hash I<this>. - -=item FETCH this, key - -Retrieve the datum in I<key> for the tied hash I<this>. - -=item FIRSTKEY this - -Return the (key, value) pair for the first key in the hash. - -=item NEXTKEY this, lastkey - -Return the next key for the hash. - -=item EXISTS this, key - -Verify that I<key> exists with the tied hash I<this>. - -The B<Tie::Hash> implementation is a stub that simply croaks. - -=item DELETE this, key - -Delete the key I<key> from the tied hash I<this>. - -=item CLEAR this - -Clear all values from the tied hash I<this>. - -=back - -=head1 CAVEATS - -The L<perltie> documentation includes a method called C<DESTROY> as -a necessary method for tied hashes. Neither B<Tie::Hash> nor B<Tie::StdHash> -define a default for this method. This is a standard for class packages, -but may be omitted in favor of a simple default. - -=head1 MORE INFORMATION - -The packages relating to various DBM-related implementations (F<DB_File>, -F<NDBM_File>, etc.) show examples of general tied hashes, as does the -L<Config> module. While these do not utilize B<Tie::Hash>, they serve as -good working examples. - -=cut - -use Carp; -use warnings::register; - -sub new { - my $pkg = shift; - $pkg->TIEHASH(@_); -} - -# Grandfather "new" - -sub TIEHASH { - my $pkg = shift; - if (defined &{"${pkg}::new"}) { - warnings::warnif("WARNING: calling ${pkg}->new since ${pkg}->TIEHASH is missing"); - $pkg->new(@_); - } - else { - croak "$pkg doesn't define a TIEHASH method"; - } -} - -sub EXISTS { - my $pkg = ref $_[0]; - croak "$pkg doesn't define an EXISTS method"; -} - -sub CLEAR { - my $self = shift; - my $key = $self->FIRSTKEY(@_); - my @keys; - - while (defined $key) { - push @keys, $key; - $key = $self->NEXTKEY(@_, $key); - } - foreach $key (@keys) { - $self->DELETE(@_, $key); - } -} - -# The Tie::StdHash package implements standard perl hash behaviour. -# It exists to act as a base class for classes which only wish to -# alter some parts of their behaviour. - -package Tie::StdHash; -@ISA = qw(Tie::Hash); - -sub TIEHASH { bless {}, $_[0] } -sub STORE { $_[0]->{$_[1]} = $_[2] } -sub FETCH { $_[0]->{$_[1]} } -sub FIRSTKEY { my $a = scalar keys %{$_[0]}; each %{$_[0]} } -sub NEXTKEY { each %{$_[0]} } -sub EXISTS { exists $_[0]->{$_[1]} } -sub DELETE { delete $_[0]->{$_[1]} } -sub CLEAR { %{$_[0]} = () } - -1; |