Re: Debug mode without using "-d"

[Ervin Hegedüs]

Hi Simon,

so many thanks for your help :).

On Sun, Dec 08, 2019 at 11:31:52PM +0100, Simon Richter wrote:
> On 08.12.19 19:46, Ervin Hegedüs wrote:
> 
> > I'ld like to control this feature through my code. I realized
> > that this option set a variable in generated source file:
> >
> >   1577  extern int yy_flex_debug;
> >   1578  int yy_flex_debug = 1;
> >
> >     if (argc > 1) {
> >         if (strcmp(argv[1], "debug") == 0) {
> >             yyset_debug(1);
> >         }
> >     ...
> >
> > but has no effect (if I use "flex" command without "-d").
> >
> > What am I missing?
> 
> The variable is initialized to 1 by default. If you want to leave the
> debug code in but disable it at runtime, your logic needs to set it to 0
> if no "debug" option was given.

ah, cool - now it works!

> Debug output from flex is usually not that useful to anyone not directly
> working on the parser, so the setting is seldom changed at runtime, and
> making it default-on if the debug code was generated allows people to
> add debug output to an existing program without changing other code,
> just by recompiling the lexer.

yes, I think it's clear for me - I'ld like to implement a parser
which will be a part of an API, and would like to give some help
the (API) users to get some debug information.

Many thanks again for your help,


regards,


a.