Date: Wed, 27 Oct 1999 10:23:48 +0400 (MSD) From: Alexey Zelkin <phantom@scorpion.crimea.ua> To: rivers@dignus.com (Thomas David Rivers), hackers@FreeBSD.org Subject: Re: X11/C++ question Message-ID: <199910270623.KAA10106@scorpion.crimea.ua> In-Reply-To: <Pine.BSF.4.10.9910262134050.29073-100000@picnic.mat.net> <199910270142.VAA31089@lakes.dignus.com>
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hi,
>> Does anyone (anyone, that is, who's coded X11 applications) know how you
>> handle X11 callbacks to C++ object methods?
>>
>> Thanks,
TDR> If you mean Xt (and possibly Motif) - the answer is "very carefully."
TDR> The Xt callbacks are C based, so you typically can't directly call a
TDR> C++ method.
TDR> But, you can have an extern "C" block that declares the call back
TDR> function (the extern "C" basically keeps any name mangling from going on)
TDR> and then, in that function, invoke the method as appropriate.
TDR> I believe you do something like:
TDR> class myclass {
TDR> void mymethod(void * arg1) {
TDR> cout << "Ha! I got to the class" << '\n';
TDR> };
TDR> }
TDR> extern "C" {
TDR> void
TDR> callback_function(arg1)
TDR> void *arg1;
TDR> {
TDR> /* Call the method */
TDR> myclass::mymethod(arg1);
TDR> }
TDR> }
Looks good except one point -- mymethod should be static, i.e.
static void mymethod (...) {
...
}
TDR> Then, you register "callback_function" as the Xt/Motif callback.
TDR> I've at least "heard" of doing that kind of thing before...
--
/* Alexey Zelkin && phantom@cris.net */
/* Tavric National University && phantom@crimea.edu */
/* http://www.ccssu.crimea.ua/~phantom && phantom@FreeBSD.org */
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