This patch introduces
a) a few doxygen comments, so that the doxygen overview is not that empty anymore.
b) the debug_message_settings.h which contains a 'Macro-composition' for managing debug outputs so you can toggle different debug-output-types. I preconfigured some of them in order to get to know the parse and eval system of octave. - I think this may help other persons too.

This may be helpful for
b.1) Debugging.
b.2) Getting to know the octave code.

You can now go into ./liboctave/util/debug_message_settings.h , take a look at the comments and change the value of VERBOSE in line 52 to one of the specified values below (or above in the comments.)

• Currently supported types are:
• - NONE
• - PARSE_TRACE (Partially implemented)
• - PARSE_DBG (Not implemented)
• - EVAL_TRACE
• - PARSE_MEASURE
• - EVAL_MEASURE

You can easily concat several options via the | operator.

 #define VERBOSE           (PARSE_TRACE|EVAL_TRACE)

The parse trace will e.g. look as follows:

 >> x = 1
 [DBG][PTR] Found identifier.
 [DBG][PTR] Found simple expression.
 [DBG][PTR] Found numeric constant.
 [DBG][PTR] Found simple expression.
 [DBG][PTR] Found assign expression.
 [DBG][PTR] Found expression.
 x =  1
 >>

If you define VERBOSE as NONE this patch will have no effect on the runtime-performance.

I hope this is helpful and I'd appreciate any feedback.

Greetings,

Lasse Schuirmann