timeSetTimer Callback Issues

I have a compilation error I can't figure out. I am calling timeSetTimer from a member function within a class. The callback function is also a member of the class.

When I compile this statement:

timeSetEvent(iDelay, 0, &wait, NULL, TIME_ONESHOT);

I get:

error C2276: '&' : illegal operation on bound member function expression

When I compile this statement:

timeSetEvent(iDelay, 0, &FOO::wait, NULL, TIME_ONESHOT);

I get:

error C2664: 'timeSetEvent' : cannot convert parameter 3 from 'void (__stdcall FOO::*)(unsigned int,unsigned int,unsigned long,unsigned long,unsigned long)' to 'void (__stdcall *)(unsigned

Any ideas?

Thanks!

How to use class member functions as callbacks?

Makes sense... Thanks!

You are welcome...

Ok... I am back with a similar issue. I've decided to place a flag in the callback function that I will clear upon execution. I have the flag as a private member of the class. When I attempt to clear it inside the callback function with:

pulsing=false;

I get:

illegal reference to data member 'FOO::pulsing' in a static member function

The error makes sense because the this pointer is not passed along. I figured declaring the flag as

static bool pulsing;

would solve this issue... but that generates an unresolved external symbol.

Any help?

You basically have two choices here...

• Using a static member. They need to be defined however, thus...
  
  Code:

  ---

  // .hpp
class foo
{
  static bool pulsing;
};

// .cpp
bool foo::pulsing = false;

  ---

• 'timeSetEvent()' allows you to pass a user-defined value as a 'DWORD_PTR'. You can use this to pass the 'this' pointer of the class instance you want to access in your callback...

I ended up using the DWORD dwUser parm to pass the pointer this to the function. I couldn't get your first example to work. I had actually tried that. It doesn't seem to like the static bool pulsing declaration. I still get the unresolved external symbol error.

Even though I have it working I would still like to know why declaring the flag as static doesn't work for me.

Thanks!

Quote:

---

Originally Posted by eeboy

Even though I have it working I would still like to know why declaring the flag as static doesn't work for me.

---

Well...without seeing the actual you tried it with, it is pretty hard to tell...nevertheless, it should have worked.