Re: string buffer

[Bruno Haible]

Pádraig Brady wrote:
> Since there are lots of appending of strings here,
> the approach taken in coreutils so far was
> to append in a large buffer allocated up front,
> or just to write to stdout.
> 
> I guess something in between is more appropriate for a lib.
> I.E. efficiently append to a string on the heap.
> This is a common operation, so maybe there are routines
> in gnulib to use for this? I previously abstracted this operation in:
> http://www.pixelbeat.org/libs/sbuf.h
> http://www.pixelbeat.org/libs/sbuf.c

In gnulib, we have mostly inlined such operations so far. If you want
to add a module 'stringbuffer', similar to the module 'linebuffer' which
we already have and which is for input, please do. This is welcome.

Back to the function that returns a relativized file name. There are
basically 3-4 common return value conventions for functions that need to
return a string.
  - Return a 'char *', to a statically allocated area. (Ex.: strerror)
  - Return a 'char *', freshly allocated. (Ex.: asprintf)
  - Pass a buffer and its length. (Ex.: gethostname)
  - Pass a buffer and a pointer to a length location. (Ex.: unistr.h)
I think some of these will also work in combination with a 'stringbuffer',
without the need to have an interface that takes a 'string_buffer *' as
argument. 
I wouldn't like to see 'filename-relative' have a dependency on 'stringbuffer',
when so many functions who produce a string don't have this dependency.

Bruno