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From: Mats Karlssohn <mats@mida.se>
Newsgroups: comp.lang.ada
Subject: Re: Compile time executed functions
Date: Wed, 28 Mar 2001 09:17:26 +0200
Organization: MIDA Systemutveckling AB
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Ted Dennison wrote:
%<
> >I have hoped to get the time to either build a small preprocessor to do
> >this kind of execution/substitution trick, or to add the same trick into
> >GNAT using some pragma(Compiler_Executed, func). Sorry to say, I don't
> >see that ammount of time in the near future.
> 
> If you are talking about being able to run pretty much *any* code at compile
> time, no that can't be done with just a "trick". I don't know of any language in
> existance (but I suppose there probably is one somewhere) that will let you do
> that. It might be doable for a self-hosted system, but for a cross-compiled
> system (which I suspect is your situation, otherwise you wouldn't be worrying
> about making the result ROMable) I don't think it would be possible at all. The
> cross compiler would also have to include a full-fledged native compiler!

This IS what I'm dreaming of. Of course a lot of restrictions on what
code is allowed to execute (sideeffects etc). Ofcourse you'll need a
native compiler to compile the initialization function (and all code
that it uses).

The analysis of the code, regarding weather it can be allowed is
probably so complex that it's best done from within the compiler,
and not in some kind of preprocessor.
I still hope to get some time to experiment with gnat (after all I
have to have the native compiler to build the crosscompiler anyway).

-- 
Mats Karlssohn, developer                         mailto:mats@mida.se  
Mida Systemutveckling AB                          http://www.mida.se
Box 64, S-732 22 ARBOGA, SWEDEN
Phone: +46-(0)589-89808   Fax: +46-(0)589-89809