GEOS Programming: 2.3 Goc and C: Macros in Goc

@define

The C programming language allows definition and use of macros, and most programmers use macros extensively. You can use the #define directive in standard C code in your GEOS programs to define macros that use only standard C code.

Similarly, you can use the @define Goc directive to create macros in Goc. (Macros must be defined with @define ; otherwise, the Goc processor will skip the #define directive and process the macro as if it were standard code to be processed normally.)

Macros in Goc have a somewhat different syntax than standard C macros though they are very similar. Some examples of simple Goc macros follow below:

@define mlply(val1,val2)					val1 * val2
@define defChunk(a)				@chunk char a[] = "text"

When using Goc macros in your code, you must preface them with the "@ " Goc marker, indicating to the processor that it is a macro. If you do not preface the macro with "@ ", then Goc will pass over it and will not process it, leaving it up to the C compiler--which will likely give an error. For example, using the second macro defined above (defChunk), you could create a number of chunks easily:

@defChunk(firstText)
@defChunk(secondText)
@defChunk(thirdText)

The above would equate to the following:

@chunk char[] firstText = "text";
@chunk char[] secondText = "text";
@chunk char[] thirdText = "text";

Using "defChunk" without the "@ " marker would most likely result in a compilation error in the C compiler.

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