WTL is template library, so i have to implement it in template library header file.
I want to implement my logic in .cpp file otherwise,  i will have to code a huge header file.
for example, in MainFrm.h
// ...
// MainFrm.h
class CMainFrame : 
    public CFrameWindowImpl<CMainFrame>, 
    public CUpdateUI<CMainFrame>,
    public CMessageFilter, public CIdleHandler
{
  //...
  void function1()
  {
    //...
  }
  void function2()
  {
    //...
  }
}
I want to have function1() and function2() in myfunction.cpp, how to do it?
Please guide.
EDIT:
Solved! thanks to Jan S. i had include myfunction.cpp into WTL project and add some lines:
MainFrm.h:
// ...
// MainFrm.h
#if 1
#include <atlframe.h>
#include <atlsplit.h>
#include <atlctrls.h>
#include <atlctrlw.h>
#include <atlctrlx.h>
#include "sampleView.h"
#include "resource.h"
#endif
// MainFrm.h
class CMainFrame : 
    public CFrameWindowImpl<CMainFrame>, 
    public CUpdateUI<CMainFrame>,
    public CMessageFilter, public CIdleHandler
{
  //...
  void functionx();
  //...
};
myfunction.cpp:
// myfunction.cpp
#include "stdafx.h" 
#include "MainFrm.h"
void CMainFrame::functionx()
{
  //...
}
 
    