#define SILC_TASK_CALLBACK ...

    Generic macro to declare task callback functions. This defines a
    function with name `func' as a task callback function.

    #define SILC_TASK_CALLBACK(func)                                        \
    void func(SilcSchedule schedule, void *app_context, SilcTaskEvent type, \
              SilcUInt32 fd, void *context)