GB.Watch

void GB.Watch ( int fd , int flag , GB_WATCH_CALLBACK callback , long param )

Asks the interpreter to watch or to stop watching a specific file descriptor.

fd is the file descriptor to watch.
flag is one of the following constants that defines the watch action:
- GB_WATCH_NONE, to stop watching.
- GB_WATCH_READ, to watch for reading.
- GB_WATCH_WRITE, to watch for writing.
- GB_WATCH_READ_WRITE, to watch for both reading and writing.
callback is the address of a function that will be called each time the fd file descriptor fulfils the condition defined by flag.
param is a long constant passed to the callback.