# Listing of doc/example-scripts/rosetta-abstract-type.tcl

## Rosetta Example: Abstract type

Define a class without instances and without implemented methods. For detailed description of this example see http://rosettacode.org/wiki/Abstract_type

Define a class AbstractQueue

Define a concrete queue (named ListQueue) based on the Abstract Queue

### Demonstrating the behavior in a shell:

Trying to create an instance of the AbstraceQueue returns an error message:

Create an instance of the concrete queue:

Enqueue and dequeue items