From: "Nicolas Cannasse" <warplayer@free.fr>
To: <Alain.Frisch@ens.fr>,
"Jacques GARRIGUE" <garrigue@kurims.kyoto-u.ac.jp>
Cc: <caml-list@inria.fr>
Subject: Re: [Caml-list] Proposal for separate compilation
Date: Fri, 28 May 2004 09:13:55 +0200 [thread overview]
Message-ID: <001f01c44483$571c3f10$ef01a8c0@warp> (raw)
In-Reply-To: <20040528.105427.68533454.garrigue@kurims.kyoto-u.ac.jp>
[...]
> > but different implementations. One solution is simply, as Nicolas
> > suggests, to store the original name of the compilation unit in the uid.
> > Still, one could imagine two modules with the same name and the same
> > interface in unrelated libraries. This would be a good argument for
using
> > reallly unique ids instead of hash. When you compile an interface a.mli,
> > you just mark a.cmi with a fresh random uid (with possibly a check that
> > the real content of a.cmi has been modified, otherwise don't touch the
> > uid). This will be used to make reference to module A from b.cmo (and of
> > course a.cmo). In other words: compilation of interfaces is given a
> > generative semantics.
>
> Yes, but by doing that you are breaking two things:
> * a .cmi does no longer depend only on the contents of the .mli
> i.e., if you recompile twice the same library, then all the
> dependencies must be recompiled, eventhough nothing has changed
> (This may make bootstrapping the compiler rather complicated!
> Every recompilation of the standard library would be incompatible.)
That's why I'm suggesting we should still use a hash of the cmi as uid, and
add a random id in order to resolve ambiguous cases only.
> * one can imagine a strange situation where you generated two
> differents .cmo with the same .cmi (i.e. two .ml for one .mli, and
> you compiled the .mli only once). Your scheme cannot cope with this
> case: the two .cmo would conflict.
> (I agree this is a bit far fetched)
This is clearly forbidden by both current and "improved" linking model, I'm
not sure we want that "feature" :)
> This looks like an attempt to solved the above compatibility problem.
> Do not change the semantics of interfaces, only the compilation of
> implementation.
> Both imports and exports of libraries have "abstract" names (in
> practice unique ids, different for import and export) and the linker
> connects imports to the corresponding exports. Sound pretty powerful,
> and theoretically nice. But you get bigger .cmo/.cmx, and linking is
> more complex.
This is also a solution, but as you told, it's more complex to implement.
I'm worried also about this complexness when using Dynamic linking . Alain's
idea - still not perfect - is simple enough to be worth implemented.
Best Regards,
Nicolas Cannasse
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next prev parent reply other threads:[~2004-05-28 7:14 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-05-21 16:32 Alain Frisch
2004-05-21 18:11 ` Richard Jones
2004-05-21 18:27 ` Nicolas Cannasse
2004-05-26 8:32 ` Xavier Leroy
2004-05-26 15:12 ` Nicolas Cannasse
2004-05-28 0:33 ` Alain Frisch
2004-05-28 1:54 ` Jacques GARRIGUE
2004-05-28 7:13 ` Nicolas Cannasse [this message]
2004-05-28 9:55 ` Alain Frisch
2004-05-28 10:14 ` Christian Lindig
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