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	return bless $self, $class;
}

sub reset {
	my ($self) = @_;

	die "Knowledge->reset() takes no arguments" if scalar(@_) != 1;

	$self->{_value} = undef;
	$self->{_setter} = undef;
}

sub set_value {
	my ($self, $value, $setter) = @_;

    die "Knowledge->set_value() takes 2 argument" if scalar(@_) != 3;
    die "Knowledge->set_value() argument 1, (VALUE) is undefined" if ! defined($value);
    die "Knowledge->set_value() argument 2, (SETTER) is undefined" if ! defined($setter);

	if(defined($self->{_value})) {
		die "Knowledge->set_value() has already been set";
	}

	$self->{_value} = $value;
	$self->{_setter} = $setter;
}

sub get_value {
	my ($self) = @_;

        die "Knowledge->get_value() takes no arguments" if scalar(@_) != 1;

	return $self->{_value};
}

sub get_setter {
	my ($self) = @_;

	die "Knowledge->get_setter() takes no arguments" if scalar(@_) != 1;

	return $self->{_setter};
}

sub is_value_set {
	my($self) = @_;

        die "Knowledge->is_value_set() takes no arguments" if scalar(@_) != 1;

	return defined($self->{_value});
}

sub set_question {
	my ($self, $question, @responses) = @_;

	if(defined($self->{_question})) {
		die "Knowledge->set_question() has already been set";
	}

        die "Knowledge->set_question() takes 2 arguments" if scalar(@_) < 3;
        die "Knowledge->set_question() argument 1, (QUESTION) is undefined" if ! defined($question);
#		This test just doesnt work for a list
#		die "Knowledge->set_question() argument 2, (RESPONSES) is undefined" if scalar(@responses) == 0;

	$self->{_question} = $question;
	push(@{$self->{_responses}}, @responses);
}

sub get_question {
	my ($self) = @_;

        die "Knowledge->get_question() takes no arguments" if scalar(@_) != 1;

	if(!defined($self->{_question})) {
		die "Knowledge->set_question() has not been set";
	}

	return ($self->{_question}, @{$self->{_responses}});
}

sub has_question {
	my ($self) = @_;

        die "Knowledge->has_question() takes no arguments" if scalar(@_) != 1;

	return (defined($self->{_question}) and !defined($self->{_value}));
}

sub name {
	my ($self) = @_;

        die "Knowledge->name() takes no arguments" if scalar(@_) != 1;

	return $self->{_name};
}

1;

=head1 NAME

AI::ExpertSystem::Simple::Knowledge - Utility class for a simple expert system

=head1 VERSION

This document refers to verion 1.2 of AI::ExpertSystem::Simple::Knowledge, released June 10, 2003

=head1 SYNOPSIS

This class handles the attributes and their values within the expert system along with the optional question that
can be asked of the user to set the value of the attribute. The valid responses to the optional question are also held.

=head1 DESCRIPTION

=head2 Overview

This is a utility class for AI::ExpertSystem::Simple

=head2 Constructors and initialisation

=over 4

=item new( NAME )

lib/AI/ExpertSystem/Simple/Knowledge.pm  view on Meta::CPAN

=item Knowledge->set_value() argument 1, (VALUE) is undefined

The correct number of arguments were supplied to the method call, however the first argument, VALUE, was undefined.

=item Knowledge->set_value() argument 2, (SETTER) is undefined

The correct number of arguments were supplied to the method call, however the second argument, SETTER, was undefined.

=item Knowledge->set_value() has already been set

This method has already been called and the value set. It cannot be called twice.

=item Knowledge->get_value() takes no arguments

When the method is called it requires no arguments. This message is given if some where supplied.

=item Knowledge->get_setter() takes no arguments

When the method is called it requires no arguments. This message is given if some where supplied.

=item Knowledge->is_value_set() takes no arguments

When the method is called it requires no arguments. This message is given if some where supplied.

=item Knowledge->set_question() takes 2 arguments

When the method is called it requires two arguments. This message is given if more of less arguments are given.

=item Knowledge->set_question() argument 1, (QUESTION) is undefined

The correct number of arguments were supplied to the method call, however the first argument, QUESTION, was undefined.

=item Knowledge->set_question() has already been set

This method has already been called and the value set. It cannot be called twice.

=item Knowledge->get_question() takes no arguments

When the method is called it requires no arguments. This message is given if some where supplied.

=item Knowledge->get_question() has not been set

The value has not been set by Knowledge->set_question() and, therefore, cannot be retrieved.

=item Knowledge->has_question() takes no arguments

When the method is called it requires no arguments. This message is given if some where supplied.

=item Knowledge->name() takes no arguments

When the method is called it requires no arguments. This message is given if some where supplied.

=back

=head1 BUGS

None

=head1 FILES

See Knowledge.t in the test directory

=head1 SEE ALSO

AI::ExpertSystem::Simple - The base class for the expert system shell

AI::ExpertSystem::Simple::Goal - A utility class

AI::ExpertSystem::Simple::Rules - A utility class

=head1 AUTHORS

Peter Hickman (peterhi@ntlworld.com)

=head1 COPYRIGHT

Copyright (c) 2003, Peter Hickman. All rights reserved.

This module is free software. It may be used, redistributed and/or 
modified under the same terms as Perl itself.