#!perl -w
use strict;

# You could write any kind of function you wanted... 
# I thought I'd go for multi-operand functions.
my %funk;
%funk = (
    'Add'        => sub { return $_[0] if not defined $_[1];
                          unshift( @_, shift( @_ ) + shift( @_ ) );
                          &{$funk{Add}}},
    'Subtract'   => sub { return $_[0] if not defined $_[1];
                          unshift( @_, shift( @_ ) - shift( @_ ) );
                          &{$funk{Subtract}}},
    'Multiply'   => sub { return $_[0] if not defined $_[1];
                          unshift( @_, shift( @_ ) * shift( @_ ) );
                          &{$funk{Multiply}}},
    'Divide'     => sub { return $_[0] if not defined $_[1];
                          unshift( @_, shift( @_ ) / shift( @_ ) );
                          &{$funk{Divide}}},
    'IsEqual'    => sub { for ( 1 .. $#_ ) { return 0 if $_[0] != $_[$
+_] } 1 },
    'IsNotEqual' => sub { &{$funk{IsEqual}} ? 0 : 1 },
);

sub Funk::TIESCALAR { bless \$_[1], $_[0] }
sub Funk::FETCH { ${$_[0]} }
sub Funk::STORE { ${$_[0]}=$funk{$_[1]} }

my $op;
tie $op, 'Funk', $op;

#Usage:
#  You now simply decide the operator you want and pass it the args:
#  $op = 'Add';
#  my $two = $op->( 1, 1 );

# Test loop:
my @testArgs = ( 3, 3 );
for ( sort keys %funk )
{
    $op = $_;
    my $answer = $op->( @testArgs );

    # print the result:
    $^A = "";
    formline "\@>>>>>>>>>>>>>>>>>>>>> = $answer\n", 
             "$_( " . join( ', ', @testArgs ) . " )";
    print $^A;
}
__END__
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