Re: SIGALRM in a class member?

From:
Ron Eggler <unknown@example.com>
Newsgroups:
comp.lang.c++
Date:
Wed, 13 Aug 2008 00:00:57 GMT
Message-ID:
<Zupok.6483$%b7.2705@edtnps82>
R Samuel Klatchko wrote:

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

Hey Samuel,

This is kinda what I do -see my other posting except that I copy my instance
like this:
gps = new INITSource(source, 51001, log, gpsDataObj, false);
Glob_INIT_i = dynamic_cast<INITSource*>(gps);

I have to cast it again because gps is from a different type (mother class
of INITSource)

--
weeks of software enineering safe hours of planing ;)

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