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[Caml-list] void/unit in C calls
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Date: 2004-02-20 (19:50)
From: Markus Mottl <markus@o...>
Subject: Re: [Caml-list] void/unit in C calls
On Fri, 20 Feb 2004, Michael Furr wrote:
> I realize this is somewhat of a pedantic question but, what is the proper
> prototype for a C function which has a parameter of type unit?
> ie:
>  external foo : unit -> unit = "foo_c"
> should foo_c be declared
>  void foo_c(void);
> or
>  value foo_c(value);
> Would it ever cause a problem on any architecture if one used the wrong
> form?

It makes a difference: you should always return Val_unit from
unit-functions implemented in C. Otherwise you might find obscure
things like:

  foo () <> ()

Or worse... - somebody reported to me that he sometimes saw programs
crash, though it isn't certain that this was the cause.

It shouldn't matter whether you pass void or value to C, I think, unless
you want to use the value - which is quite unlikely.


Markus Mottl          http://www.oefai.at/~markus          markus@oefai.at

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