Re: [exim] Idea: Predefined macros

On Wed, 2007-05-02 at 23:10 +0100, Jason_Meers wrote:
> In my mind there are two points here:
>
> 1) To include (or not to include) predefined macros
> 2) The overheads of processing additional macros

I think we need some use cases first. CONFDIR was mentioned, but IMHO
this could just as easily be handled by letting .include use some
compiled-in directory as its base directory. (I don't think this
affects backwards compatibility, since today cwd is basically
non-deterministic.)

I guess you could add macros for inspecting the build environment, e.g.,
HAS_SSL, HAS_LOOKUP_LDAP, HAS_MAILDIR etc., but these are not
interesting to override, so you might as well extend .ifdef (e.g., a new
directive called .hasfeature)

> I am assuming that these "predefined macros" relate to the exim
> environment itself and can be set at startup/restart. By this I mean
> that each macro will only have one value at any particular time and that
> we can determine that value when exim starts, and that these macro
> values are not not going to change value per message, or per delivery

they can change if you reinvoke Exim on itself in a transport with
-DFOO=$somevariable in the command line.

--
Kjetil T.