Re: SIGALRM in a class member?

From:
R Samuel Klatchko <rsk@moocat.org>
Newsgroups:
comp.lang.c++
Date:
Tue, 12 Aug 2008 16:57:40 -0700
Message-ID:
<X7OdnTTkmfDovj_VnZ2dnUVZ_vudnZ2d@speakeasy.net>
Ron Eggler wrote:

signal( SIGALRM, sendHeartbeat );
alarm(atoi(INITSource::XMLread(inBufstr,"Cyclic").c_str()));
but the problem is signal wouldn't allow me to have a function pointer to a
member method like INITSource::sendHeartbeat. If I need to do it this way I
would end up in crazy static declarations and linker conflicts - I have
gone there already and apparently didn't solve it...


You can do this with a forwarding function that is a static member (you
can also do it with a non-member function). Because signal does not
give you a way to attach some caller defined data, you will also need a
static member variable to hold a pointer to the instance of the class
you want to use:

   foo.h:
   class foo
   {
   public:
       foo()
       {
           signal(SIGALRM, sighandler_trampoline);
           singleton = this;
       }

   private:
       static void sighandler_trampoline(int sig)
       {
           singleton->sighandler(sig);
       }

       void sighandler(int sig)
       {
           // add your logic here
       }

       static foo *singleton;
   };

   foo.cpp:
   foo *foo::singleton = 0;

samuel

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