How do I pass a ptr to member fn to a signal handler,X event callback,etc?
Don’t. Because a member function is meaningless without an object to invoke it on, you can’t do this directly (if The X Windows System was rewritten in C++, it would probably pass references to OBJECTS around, not just pointers to fns; naturally the objects would embody the required function and probably a whole lot more). As a patch for existing software, use a top-level (non-member) function as a wrapper which takes an object obtained through some other technique (held in a global, perhaps). The top-level function would apply the desired member function against the global object. E.g., suppose you want to call Fred::memfn() on interrupt: class Fred { public: void memfn(); static void staticmemfn(); //a static member fn can handle it //… }; //wrapper fn remembers the object on which to invoke memfn in a global: Fred* object_which_will_handle_signal; void Fred_memfn_wrapper() { object_which_will_handle_signal->memfn(); } main() { /* signal(SIGINT, Fred::memfn); */ //Can NOT do this s
