Re: stupid way to hang lyx

[Angus Leeming]

On Friday 05 October 2001 15:44, Jean-Marc Lasgouttes wrote:
> >>>>> "Angus" == Angus Leeming <[EMAIL PROTECTED]> writes:
> 
> Angus> On Friday 05 October 2001 15:14, Jean-Marc Lasgouttes wrote:
> >> >>>>> "Jules" == Jules Bean <[EMAIL PROTECTED]> writes:
> >> 
> >> >> It does not crash, it hangs...
> >> 
> Jules> I'd still call it a bug. LyX should fork() before doing
> Jules> something like that...
> >>  I guess the problem is the same with the converters code (if we
> >> have a bogus converter). However, the converters are forced to wait
> >> for completion before doing the next step. So how do we do that?
> 
> Angus> You can pass a pointer to a function to Systemcalls. This
> Angus> function is called on completion of the forked process. Why not
> Angus> split the conversion code into two and place the "after
> Angus> conversion" stuff in this function?
> 
> So, if the converter hangs, LyX hangs waiting for completion, no?

That's not my understanding of the syscall.h comments:

        /// Uses fork() and execvp()
        DontWait
        };

        /// Callback function gets commandline and return value from child
        typedef void (*Callbackfct)(string cmd, int retval);
        
        ///
        Systemcalls();
        
        /** Generate instance and start child process.
            The string "what" contains a commandline with arguments separated 
            by spaces.
            When the requested program finishes, the callback-function is 
            called with the commandline and the return value from the program.
            The instance is automatically added to a timer check if starttype 
            is DontWait (i.e. background execution). When a background child
            finishes, the timer check will automatically call the callback
            function.
        */
        Systemcalls(Starttype how, string const & what, Callbackfct call = 0);

Would not this do as you desire:

        Systemcalls::Callbackfct convert_callback = &convert_continue;

        Systemcalls convert(Systemcalls::DontWait, 
                              "convert file.eps XPM::file.xpm",
                              convert_callback);

        // continue main LyX loop
        ...



        void convert_continue(string cmd, int retval)
        {
                // Ok, we have the file, now deal with it...
        }