11 years, 1 month ago.

FunctionPointer?

Hi all,

I'm very impressive with mbed library and i want to understand a little about this library but i'm very confused with the use of class FunctionPointer:

typedef void (*pvoidf_t)(void); / A class for storing and calling a pointer to a static or member void function

• / class FunctionPointer { public: / Create a FunctionPointer, attaching a static function
• @param function The void static function to attach (default is none)
• / FunctionPointer(void (*function)(void) = 0);

/ Create a FunctionPointer, attaching a member function

• @param object The object pointer to invoke the member function on (i.e. the this pointer)
• @param function The address of the void member function to attach
• / template<typename T> FunctionPointer(T *object, void (T::*member)(void)) { attach(object, member); }

/ Attach a static function

• @param function The void static function to attach (default is none)
• / void attach(void (*function)(void) = 0);

/ Attach a member function

• @param object The object pointer to invoke the member function on (i.e. the this pointer)
• @param function The address of the void member function to attach
• / template<typename T> void attach(T *object, void (T::*member)(void)) { _object = static_cast<void*>(object); memcpy(_member, (char*)&member, sizeof(member)); _membercaller = &FunctionPointer::membercaller<T>; _function = 0; }

/ Call the attached static or member function

• / void call();

pvoidf_t get_function() const { return (pvoidf_t)_function; } private: template<typename T> static void membercaller(void *object, char *member) { T* o = static_cast<T*>(object); void (T::*m)(void); memcpy((char*)&m, member, sizeof(m)); (o->*m)(); }

void (*_function)(void); static function pointer - 0 if none attached void *_object; object this pointer - 0 if none attached char _member[16]; raw member function pointer storage - converted back by registered _membercaller void (*_membercaller)(void*, char*); registered membercaller function to convert back and call _member on _object };

Can anyone help me understand some declaration in this class template<typename T> FunctionPointer(T *object, void (T::*member)(void))

I don't understand the declaration T::*member, I never have seen it before, Can you give me an explanation and an example use this declaration. Thanks in advanced!