Chapter 10. Abstracted Functions

   /*--------------------------------------------------------------------
    * Function:    anyos_system
    * Returns:     doesn't return
    * Description: A wrapper for the system() function to allow for alternate
    *              code in QNX.
    *------------------------------------------------------------------*/
   function anyos_system(call, sig)
   {
     system(call);
   }
   

The Gamma functions block_signal and unblock_signal signal are used for deactivating signals while the system call is made. The signal has to be re-defined using the Gamma signal function once block_signal has been used.

   /*--------------------------------------------------------------------
    * Function:    anyos_system
    * Application: common 
    * Returns:     t or nil
    * Description: A wrapper for the Gamma system() function that blocks
    *              signals while making a call, then reassigns a signal
    *              and unblocks the signals.  This is necessary for QNX4,
    *              and perhaps QNX6, because in that OS a system() call
    *              emits a signal.  
    *------------------------------------------------------------------*/
   function anyos_system(call, sig)
   {
     block_signal(sig);
     system(call);
     signal(sig, `anygui_sigchild());
     unblock_signal(sig);
   }
   

For Linux we assume that help files are not installed on the system, but that a browser is installed. Thus, this function walks through a list of browsers and starts the first available one, pointing it to the on-line Cogent documentation for the Demo and Tutorials. We use the find_on_path fuction to locate a browser that is actually installed.

   /*--------------------------------------------------------------------
    * Function:    anyos_help
    * Returns:     function
    * Description: Starts up a browser and displays the Tutorial docs.
    *------------------------------------------------------------------*/
   function anyos_help()
   {
     local url = "http://developers.cogentrts.com/cogent/cogentdocs/booktu.html";
     local browser, browsers = list("galeon", "mozilla", "lynx", "opera",
                                    "dillo", "netscape", "w3m", "netrik",
                                    "skipstone", "amaya", "phoenix", "elinks");
     local b_length = length(browsers);
   
     for (i = 0; i < b_length; i++)
       {
         browser = car(nth_cdr(browsers,i));
         if (find_on_path(browser))
           {
             system(string(browser, " ", url, " &"));
             i = b_length;
           }
         else if(i == (b_length - 1))
           anygui_makemsg(string("\nSorry, your browser isn't supported. ",
                             "Try installing one of these: \n",
                             browsers, "\n\n",
                             "Or modify the anyos_help() function, ",
                             "line 60, in lib/linux.d\n",
                             "and add your browser to the list.\n"));
       }
   }
   

For QNX running Photon, we assume that the Helpviewer is available to view the documentation. We use the Gamma is_file function to make sure the documentation has been installed in the Helpviewer. Then we use the Gamma/Photon functions PxHelpTopicRoot and PxHelpTopic to set the Helpviewer to the proper page. When QNX 6 is running GTK, the Px* functions are not readily available, so we use Voyager to view the documentation.

   /*--------------------------------------------------------------------
    * Function:    anyos_help
    * Returns:     t or nil
    * Description: Starts up the Helpviewer and displays the Tutorial docs.
    *------------------------------------------------------------------*/
   function anyos_help()
   {
     local help_url = "/usr/cogent/help/cogent-set/booktu/booktu.html";
     
     if (is_file(help_url))
       {
         if (_gui_ == "Photon")
           {
             /* Use Helpviewer */
             PxHelpTopicRoot("/Cogent Documentation/Cogent Tools Demo and Tutorial");
             PxHelpTopic("booktu.html");
           }
         else
           {
             /* Use Voyager */
             help_url = "http://developers.cogentrts.com/cogent/cogentdocs/booktu.html";
             system(string("voyager -u ", help_url, " &"));
           }
       }
     else
       anygui_makemsg(string("\nSorry, the Cogent Tools Demo and Tutorial",
                             "\nmanual is not available on your system.\n",
                             "\nPlease check your",
                             "\nCogent Documentation installation.\n\n"));
   }