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#!/usr/bin/env perl -w
# SET UP A WINDOW HIERARCHY
package Window;
my $id = 1;
sub new { bless { id=>$id++ }, ref($_[0])||$_[0] }
# SET UP DISPATCH TABLE
my %handler;
sub initialize
{
my ($arg1,$arg2,$arg3,$handler) = @_;
$handler{$arg1}{$arg2}{$arg3} = $handler;
}
initialize "Window", "Command", "Mode"
=> sub {
print "Window $_[0]->{id} can't handle a ",
ref($_[1]), " command in ",
ref($_[2]), " mode\n";
};
initialize "Window", "Command", "OffMode"
=> sub { print "No window operations available in OffMode\n" };
initialize "ModalWindow", "Reshape", "Mode"
=> sub { print "Modal windows can't ",
"handle reshape commands\n"
};
initialize "ModalWindow", "Accept", "Mode"
=> sub { print "Modal window $_[0]->{id} accepts!\n" };
initialize "ModalWindow", "Accept", "OffMode"
=> sub { print "Modal window $_[0]->{id} ",
"can't accept in OffMode!\n"
};
initialize "MovableWindow", "Move", "OnMode"
=> sub { print "Moving window $_[0]->{id}!\n" };
initialize "ResizableWindow", "Resize", "OnMode"
=> sub { print "Resizing window $_[0]->{id}!\n" };
initialize "ResizableWindow", "MoveAndResize", "OnMode"
=> sub { print "Moving and resizing window $_[0]->{id}!\n" };
my %ancestors = ();
sub ancestors
{
no strict "refs";
my ($class) = @_;
return @{$ancestors{$class}} if $ancestors{$class};
my @ancestry = ( $class );
foreach my $parent ( @{$class."::ISA"} )
{
push @ancestry, $parent, ancestors($parent);
}
$ancestors{$class} = \@ancestry;
return @ancestry;
}
sub handle
{
my ($arg1, $arg2, $arg3) = (ref($_[0]),ref($_[1]),ref($_[2]));
my $handler = $handler{$arg1}{$arg2}{$arg3};
if (!$handler)
{
my @ancestors1 = ancestors($arg1);
my @ancestors2 = ancestors($arg2);
my @ancestors3 = ancestors($arg3);
SEARCH:
foreach my $anc3 (@ancestors3)
{
foreach my $anc2 (@ancestors2)
{
foreach my $anc1 (@ancestors1 )
{
$handler = $handler{$anc1}{$anc2}{$anc3};
next unless $handler;
$handler{$arg1}{$arg2}{$arg3} = $handler;
last SEARCH;
}
}
}
}
die "No handler defined for " . join ',', map {ref} @_
unless $handler;
$handler->(@_);
}
package ModalWindow; @ISA = qw( Window );
package MovableWindow; @ISA = qw( Window );
package ResizableWindow; @ISA = qw( MovableWindow );
# SET UP A COMMAND HIERARCHY
package Command;
sub new { bless {}, ref($_[0])||$_[0] }
package ReshapeCommand; @ISA = qw( Command );
package Accept; @ISA = qw( Command );
package Move; @ISA = qw( ReshapeCommand );
package Resize; @ISA = qw( ReshapeCommand );
package MoveAndResize; @ISA = qw( Move Resize );
# SET UP A MODE HIERARCHY
package Mode;
sub new { bless {}, ref($_[0])||$_[0] }
package OnMode; @ISA = qw( Mode );
package ModalMode; @ISA = qw( Mode );
package OffMode; @ISA = qw( Mode );
package main;
# CREATE SOME WINDOWS...
@window = (
new ModalWindow,
new MovableWindow,
new ResizableWindow,
);
# ...AND SOME COMMANDS...
@command = (
new Move,
new Resize,
new MoveAndResize,
new Accept,
);
# ...AND SOME MODES...
@mode = (
new OffMode,
new ModalMode,
new OnMode,
new OnMode,
new OnMode,
);
# AND INTERACT THEM ALL...
srand(0);
for (1..100000)
{
$w = $window[rand @window];
$c = $command[rand @command];
$m = $mode[rand @mode];
print "handle(",ref($w),",",ref($c),",",ref($m),")...\n\t";
eval { $w->handle($c,$m) } or print $@;
}
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