From: Neil Jerram <neil@ossau.uklinux.net>
To: ludo@gnu.org (Ludovic Courtès)
Cc: guile-devel@gnu.org
Subject: Re: FFI and disjoint types
Date: Mon, 01 Mar 2010 20:49:58 +0000 [thread overview]
Message-ID: <87hbozvkax.fsf@ossau.uklinux.net> (raw)
In-Reply-To: <87sk8kgm5o.fsf@gnu.org> ("Ludovic Courtès"'s message of "Mon, 01 Mar 2010 15:18:59 +0100")
ludo@gnu.org (Ludovic Courtès) writes:
> Hello,
>
> The nice thing about SMOBs is that they allow disjoint C types to be
> mapped to disjoint Scheme types.
>
> With ‘(system foreign)’, C pointers are mapped to Scheme foreign
> objects, regardless of the type of object pointed to. Thus, to get
> disjoint types in Scheme, foreign objects would need to be boxed in
> structs (since structs are the only way to create disjoint types from
> Scheme).
>
> If this analysis is correct, the resulting code may be somewhat
> inefficient since we end up boxing C pointers twice.
>
> Is this correct? Thoughts?
Sounds reasonable. Perhaps (system foreign) could add a way of
declaring foreign pointer types, and of allowing code to state the type
of a pointer at the time of boxing it.
Neil
next prev parent reply other threads:[~2010-03-01 20:49 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-01 14:18 FFI and disjoint types Ludovic Courtès
2010-03-01 20:49 ` Neil Jerram [this message]
2010-03-03 12:24 ` Andy Wingo
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