A.1. Overview

The GridTurtle test programs are a collection of programs which exercise basic capabilities of the defobj, collections, and activity libraries. These programs are always run on each new release of these libraries as a partial test. For the time being they also serve to show examples of working code that exercise basic capabilities or accomplishes particular tasks.

Note, however, that these are not good examples to learn from, or examples to emulate! The programs are not particularly well-designed as either a systematic test or a useful series of tutorial examples, but until there's anything else they help serve for both. To serve their role as test programs some of these examples deliberately make use of the more obscure and low-level features of the libraries they exercise. Mixed in are examples of many basic code fragments an application might need. So be selective in what you use, and read the comments on each program below.

Most of the programs in this directory use a simple type of object called a "GridTurtle." This type of object is an agent that move around on a two-dimensional grid, always moving in a current direction that it maintains internally. This agent is like a "turtle" of the original Logo system, except that its position is constrained to discrete integer values of its X-Y coordinates, and its direction is always one of the four orthogonal directions north, east, south, or west. The GridTurtle object type is implemented using the library interface conventions of the defobj library, and is itself a defined module that must be initialized by any program.