#
# Implement a simple stack in terms of a list.
#
=pod
=head1 Stack
An object oriented implementation of a Stack data structure.
Stacks are first in last out data structures.
=head1 Member functions:
=cut
package Stack;
=pod
=head2 new
Creates a new instance of a stack.
my $stack = Stack->new();
=cut
sub new {
my $class = shift; # Class name.
my $self = []; # Create an empty list to represent the stack.
bless($self, $class); # Turn this into an object and..
return $self; # Return it.
}
=pod
=head2 push
takes an item and pushes it onto the back end of the stack.
my $stack = Stack->new();
$stack->push(something);
=cut
sub push {
my $self = shift; # Gets the list...
my $item = shift; # The item to push.
push(@$self,$item);
}
=pod
=head2 pop
Returns the item at the top of the stack: does a pop.
my object = Stack->new();
my $item = object->pop();
=cut
sub pop {
my $self = shift;
return pop(@$self);
}
1;
=pod
=head1 Internal implementation details
Stacks are implemented as lists. Thus a stack is a thinly disguised
list with push and pop wrappers. Since PERL is a dynamically typed
language, stacks can contain any data type ... including a
heterogenous collection of types.
=cut
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