Preprocessor directives

Genero Business Development Language (BDL) supports preprocessing instructions, which allow you to write macros and conditional compilation rules.

&include "myheader.4gl"
FUNCTION debug( msg )
  DEFINE msg STRING
&ifdef DEBUG
  DISPLAY msg 
&endif
END FUNCTION

Note: Use the preprocessor with care, and only when there is no native language solution. Do not overcrowd your source code with preprocessing directives, that would make the code unreadable and unmaintainable.