4.2 Defining new entity types

The define statement can be used to define new types of entities. For example, the world file from the previous section can be re-written in a more concise form as follows:

# This world file creates two robots with lasers.
# It uses the 'define' construct to define a new type of entity.

environment ( file "cave.pnm" scale 0.03 )

define myrobot position ( player() laser() )

myrobot ( name "robot1" port 6665 pose [1 1 0] )
myrobot ( name "robot2" port 6666 pose [2 1 0] )

New entities are defined using define newentity oldentity (...). For example, the line:

define myrobot position ( player() laser() )

defines a new myrobot entity type composed of the primitive position, player and laser entities. This entity may be instantiated using the standard syntax:

myrobot ( name "robot1" port 6665 pose [1 1 0] )

This entry creates a position device named robot1 that has both player and laser devices attached.