9.8. Stop Processes - stop_processes

   /*--------------------------------------------------------------------
    * Function:    stop_processes
    * Returns:     t or nil
    * Description: Gives us the option of stopping a single child process or
    *              multiple child processes.  Calls kill_child() to actually
    *              stop a process.
    *------------------------------------------------------------------*/
   function stop_processes(prog? = nil, process_name = nil)
   {
     try
       {

The code for this function is wrapped in a Gamma try/catch block, to demonstrate how the process can be protected from errors arising from this function.

         if(process_name != nil)
           {
           /* Kill a specified child, looking it up in the list of known
            * children.  We look it up by name, even though the association
            * list is by process ID.  This means that we have to traverse
            * the list of children ourselves to find the proper name.
            */
             with x in Children do
               {
                 if (cadr (x) == process_name)
                   {
                     child = x;
                     if (child)
                       kill_child(child, prog, process_name);
                   }
               }

The Gamma statements and functions used here are the with statement to walk a list and perform an action, the cadr and car functions to find those parts of a list, and the kill function to send a signal to a process.

           }
         else
           /* Kill all the children. */
           with child in Children do
             {
               prog = car(cdddr(child));
               process_name = cadr(child);
               if(prog && process_name)
                 {
                   kill_child(child, prog, process_name);
                   usleep(10000);
                 }
             }
       }
     catch
       {        
         princ("Error:\n", _error_stack_, "\n");
       }
   }