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From: Richard Jones <rich@annexia.org>
To: micha <micha-1@fantasymail.de>
Cc: caml-list@inria.fr
Subject: Re: [Caml-list] coding c++ enum type
Date: Sat, 24 Feb 2007 10:52:50 +0000	[thread overview]
Message-ID: <20070224105250.GA24014@furbychan.cocan.org> (raw)
In-Reply-To: <45E00103.9020809@fantasymail.de>

On Sat, Feb 24, 2007 at 10:10:27AM +0100, micha wrote:
> 
> when interfacing to c, what is the preferred method to represent enums 
> which are used as flags in c?
> I can choose between:
> 1. using a variant type and  a list of those variants to represent the 
> or-ed flags. Then I have to iterate over the list to calculate the 
> combined flag value.
> 
> 2. I can export global variables initialized with the real value of the 
> flags and a function which combines  (with "or") them together,
> 
> Is one method better than the other?

I don't know about preferred, but most libraries seem to be using the
list approach (1).  See for example to source to Unix.openfile:

http://camlcvs.inria.fr/cgi-bin/cvsweb/ocaml/otherlibs/unix/open.c?rev=1.8.2.3;content-type=text%2Fx-cvsweb-markup

(actually, convert_flag_list:
http://camlcvs.inria.fr/cgi-bin/cvsweb/ocaml/byterun/alloc.c?rev=1.29;content-type=text%2Fx-cvsweb-markup )

Rich.

-- 
Richard Jones
Red Hat UK Limited


  reply	other threads:[~2007-02-24 10:52 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-24  9:10 micha
2007-02-24 10:52 ` Richard Jones [this message]
2007-02-24 21:33 ` [Caml-list] " Nathaniel Gray

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