Global Variables Explained › Global Variable Basics and OPS/REXX › OPS/REXX Compound Symbols

OPS/REXX Compound Symbols

Compound symbols let you establish an accurate and efficient way to address values. By design, they are a good way to implement tables or arrays.

An OPS/REXX compound symbol is a named object that you can assign a value or data to. It is a powerful kind of variable because one or more variables can be included in the name of the compound symbol itself. In other words, what makes a compound symbol unique is that a portion of the name of the compound symbol itself can be a variable.

Let us back up a little. Typically, the name of the most simple type of a variable is an identifiable constant; most likely a character string.

On the other hand, consider a variable that is a compound symbol:

• It can have one or more fields of assignable, variable data in its name.
• It is identified first by the constant string portion of its name, the stem, and subsequently identified by the variable portion of its name, the tail.

Example: Compound Symbols

An analogy of this is the address system of a city.

In this analogy:

• A one dimensional, simple variable, which has only a constant string for a name, is like an address that consists only of a street name.
• A two-dimensional compound symbol, one that has a constant stem and a variable as part of the name, is like an address that includes both a street name and a number.

For more information about compound symbols, see THE REXX LANGUAGE: A Practical Approach to Programming by M.F. Cowlishaw (Prentice Hall, 1990).