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From: wagner@smith.cs.unc.edu (Michael Wagner)
Newsgroups: comp.lang.c++
Subject: UNIX signals in C++
Message-ID: <2523@borg.cs.unc.edu>
Date: 22 Mar 91 18:48:57 GMT
Sender: news@cs.unc.edu
Organization: University of North Carolina, Chapel Hill
Lines: 58
Originator: wagner@smith


A week or so ago, I posted news asking about 
UNIX signals in C++.  As many of you may
recall, the basic problem is that the signal()
call expects a pointer to a function as its
second parameter.

Here's the solution that worked (note that
the SIG_PF worked with Interviews' <signal.h>
file, though SIG_PFV worked with Sun's AT&T
<signal.h>):

/******************************/

// an ugly but invaluable kludge from Jon Leech

/*  A *global* pointer to the object whose
method is to be invoked upon receiving SIGINT.
The handler has no way of getting at local variables.
*/

    Texted *t;

/* This declares a signal handler.  */

    SIG_PF sighook(int, SIG_PF) {
        // Invoke the method
        t->Update();
    }

/********************************/

void Texted::Update() {

   signal(SIGUSR1, (SIG_PF)sighook);
   printf("Update invoked!\n");
   .
   .
   .
}
.
.
.

Texted::Texted () {

   signal(SIGUSR1, (SIG_PF)sighook);
   .
   .
   .
}
.
.
.

The "Jon Leech" mentioned is leech@cs.unc.edu.
I hope this save's someone some time and
agony.