Re: Provide a means to activate dynamically the debug traces

[Akim Demaille]

Le 14 janv. 09 à 11:16, Akim Demaille a écrit :

> Le 10 janv. 09 à 22:25, Ralf Wildenhues a écrit :
>
> > > So what do you recommend to store persistent information?  A  
> > > function
> > > that returns some static variable (sort of a singleton)?  Or an
> > > additional argument everywhere (gee...).  Maybe I can do it using
> > > advices to hand over the verbosity flags, but that does sound like a
> > > nuisance for the API.
> >
> > A lt_dlget* and a lt_dlset* function, if the user needs to be able to
> > provide a type.  Don't provide the user with a direct pointer if you
> > don't have to.
> >
> > Note that I didn't say global variables are bad, although they are
> > obviously bad, too, for two reasons: slow access, and, well,  
> > globality.
> > Assume that you write a library that uses ltdl internally, and I use
> > your library in a program that also links against a completely  
> > different
> > library that also uses ltdl.  You'll most likely not want  
> > interference.
> > Well, in your case I'm not so sure.  But if not, then adding a module
> > loading advisor to change verbosity would seem appropriate.
>
> I thought about this, and I think that the best option would be to  
> have a callback function with  a signature more or less like:
>
> void log(void* user_data, level_type level, const char* format, ...);

Here is my proposal.

There are a few issues on which I'd be happy to have feedback:

- I discovered slist only afterwards, and I did not convert
  my code to use it.  I believe it would bring nothing useful,
  because we really need no specific features here.  Using
  slist would probably require more auxiliary structures and
  routines.  But I can understand the advantages of reusing
  slist.

- This interface is not convenient for messages that are forged
  in several pieces (first "%s", and then "%s\n").  syslog does
  not support them, so maybe I should just always require the log
  message to be a \n-ending line?  It is annoying for
  lt_dlloader_dump.  Maybe in this case I should forge a dynamic
  string first, and log it afterwards, instead of logging several
  lines.

- I have not decided what LEVELs should be.  We could use
  syslog's values.  No strong opinion here.  Or a bitfield?

- I have to address stdarg portability, doc, tests, NEWS etc.

0001-Provide-support-for-user-logging-functions.txt
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