Re: Batons? Was: RFC: C/C++ preprocessor macro support for GDB

[Andrew Cagney <ac131313 at cygnus dot com>]

> The GDB macro patch only uses one kind of baton:
> 
> + /* A function for looking up preprocessor macro definitions.  Return
> +    the preprocessor definition of NAME in scope according to BATON, or
> +    zero if NAME is not defined as a preprocessor macro.
> + 
> +    The caller must not free or modify the definition returned.  It is
> +    probably unwise for the caller to hold pointers to it for very
> +    long; it probably lives in some objfile's obstacks.  */
> + typedef struct macro_definition *(macro_lookup_ftype) (const char *name,
> +                                                        void *baton);
> + 
> + 
> + /* Expand any preprocessor macros in SOURCE, and return the expanded
> +    text.  Use LOOKUP_FUNC and LOOKUP_FUNC_BATON to find identifiers'
> +    preprocessor definitions.  SOURCE is a null-terminated string.  The
> +    result is a null-terminated string, allocated using xmalloc; it is
> +    the caller's responsibility to free it.  */
> + char *macro_expand (const char *source,
> +                     macro_lookup_ftype *lookup_func,
> +                     void *lookup_func_baton);
> 
> Since this would be the only use of the term "baton" in the entire
> source tree, it's not exactly helping people understand things more
> there.  In the Subversion code base, things are different, since it's
> widely used.

The dwarf2 expression stuff contained the word.  It is this second 
occurance that caught my eye and got me wondering :-)

> I'm open to suggestions.  If folks think it's too cutesy, I'll change
> it to whatever they want.

For the same situtation, bfd's map_over_sections uses ``obj''.  GDB is 
similar, catch_exceptions has ``func, func_args'', ui_file_put has 
``write, dest''.  Objects are described has having ``state'' or ``context''.

enjoy,
Andrew