Category: | Miscellaneous |
Author/Contact Info | /msg runrig |
Description: | An experiment in AUTOLOAD and lvalue subs which resulted in
a sort of combination of Hash::AsObject and Tie::SecureHash (update: actually more simply like Tie::Hash::FixedKeys or Hash::Util::lockkeys). The hash is 'secure' as long as you only access it as an object using methods, but you are free to add keys when directly accessing it as a hash ref. In the interest of keeping it simple, I'm not going to worry about handling keys like 'isa', 'can', 'AUTOLOAD', 'DESTROY', or '*::*'. And this definitely breaks can().
Updated/fixed code so that lvalue methods work better.(see reply node) |
#!/usr/bin/perl package Hash::AsObj; my %sub_class; sub new { my $class = shift; my $href = { @_ }; my $sub_class; # Keep hashes with the same set of keys in # the same package my $class_key = join "~", sort keys %$href; if ( exists $sub_class{$class_key} ) { $sub_class = $sub_class{$class_key}; } else { ( $sub_class = "$href" ) =~ tr/()/__/; $sub_class{$class_key} = $sub_class; } @{"${class}::Data::${sub_class}::ISA"} = "Hash::AsObj::Data"; bless $href, "${class}::Data::$sub_class"; } package Hash::AsObj::Data; use Carp (); sub DESTROY { 1 } sub AUTOLOAD : lvalue { my ( $class, $method ) = $AUTOLOAD =~ /^(.*)::(.+)$/ or Carp::croak "Invalid call to $AUTOLOAD"; Carp::croak "Can't locate object method $method via package $class" unless exists $_[0]->{$method}; *$AUTOLOAD = sub : lvalue { my $self = shift; if (@_) { $self->{$method} = shift; return $self; } $self->{$method}; }; goto &$AUTOLOAD; $Hash::AsObj::foo; } package main; use strict; use warnings; my $hobj = Hash::AsObj->new( a=>1, b=>2, c=>3 ,e=>5 ); print $hobj->a, "\n"; # It's an lvalue method! $hobj->a++; print $hobj->a, "\n"; # Or supply an argument to set values # I like method chaining - Your opinion may differ $hobj ->b(5) ->c(6); print "b: ", $hobj->b, " c:", $hobj->c, "\n"; # Error - this key doesn't exist print $hobj->d; |
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Replies are listed 'Best First'. | |
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Re: Hash::AsObj
by runrig (Abbot) on Jun 02, 2004 at 18:25 UTC |
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