🚀 go-pugleaf

No matter how many times i read about callback functions, i could never
really grasp them. It often depends on the information is presented. With
respect to callbacks, a little light flickered on, and here is an
explanation for anyone dense as hardwood like myself. - and if you don't
like it, oh well.

Callback - the passing of your own function as a parameter into another
function. Consider the call.

void __fastcall TForm1::Button1Click(TObject *Sender){
    std::auto_ptr<TComboBox>CB(new TComboBox(this));
    SomeFunction( MyFunc, CB);
}

Now SomeFunction may be something you have written to retrieve a list of all
say all process names.. ie.

BOOL WINAPI SomeFunction(PROCENUMPROC myfunc, LPARAM lParam){
   // ...some code..e.g getting a the next process in a snapshot list.  now
call your own function MyFunc.e.g.

  while(MyFunc(processname, lParam) && ProcessesRemain){
         //pass in a var from this func, AND a var from your calling vcl
program
        if(dada)
           ProcessesRemain = false;
  }
}

...and MyFunc...
BOOL CALLBACK MyFunc(char*  processname, LPARAM lParam){
   TComboBox* cb = (TComboBox*)lParam; //do a cast
    cb->Items->Add(AnsiString(processname));
    return true;
}

In essence then, MyFunc is passed into SomeAPICallbackFunction. In this
example, each process is iterated using snapshot.
With each process found, a call to MyFunc is made, passing in the name of
the process.. and in this instance a link to your calling program, a combo
box.

rgds Angus.