Re: [xml] functions using varargs

["Petr Kozelka" <pkozelka centrum cz>]

Hello Daniel,

> > Is there any option to receive the text already formated ? It seems that it
would (again) require extending the API... or is there
> > any simpler option that I missed ?
>
>    Valid point. There is no such API. I need to think more about it
> first.
>    What's happen when one of the existing callbacks contains only
> the formatting string and no other parameter. I'm not too enthusiastic
> about duplicating the full error API, and would prefer make it an
> option to change the existing behaviour.

I was experimenting with one solution - in few words, exported C formater - and
it seems to be easy to both implement and use:

- I added a new function, to "error.c" (hopefully the correct place):
---------------------
int
xmlFormatMessage(char* buf, const char** msg)
{
    va_list args;
    int sz;
    va_start(args, *msg);
    sz = vsprintf(buf, *msg, args);
    va_end(args);
    return sz;
}
---------------------
- added the relevant entry to libxml2.def.src
- (and should also add it to error.h)

Now, in my Pascal handler, I just call this formater, passing back address of
the argument:
---------------------
procedure myGenericErrorFunc(ctx: pointer; msg: PChar); cdecl;
var
  s: String;
begin
  SetLength(s, 10000);
  SetLength(s, xmlFormatMessage(PChar(s), @msg)); // <-- HERE
  OutputDebugString(PChar(s));
end;
---------------------

The code here is meant just to show the idea; I think it is really simple and is
usable the same way for SAX and any other message reporting functions.
What do you think about the approach ?

Petr