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Logtalk - Object oriented extension to Prolog
Release 2.17.1

Copyright (c) 1998-2004 Paulo Moura.  All Rights Reserved.
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To load all objects in this example consult the bricks.loader utility
file (note that the *.loader files are Prolog files).

You will need to load the objects in the roots and relations 
examples (consulting the corresponding roots.loader and relations.loader 
files).

You will also need to consult the following files in the library directory: 
events.loader, types.loader, metapredicates.loader, and hierarchies.loader.
Alternatively, you may load the library all.loader file to load all library 
entities.

This folder contains an example of representation and handling of
relations using events. We have instances of class brick and a binary
brick_stack relation between the bricks. Every time we move a brick, we
want the bricks on top of it to move along. If we break the stack by
moving a middle brick, we want to automatically destroy the
corresponding relation tuple.

It's instructive to use the event debugger in the Logtalk library (loader 
file debugging.loader) to better understand this example. Set spy points 
in all brick instances and then activate the debugger.