The CCmdUI Class
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When it routes an update command to its handler, the framework passes the handler a pointer to a CCmdUI object (or to an object of a CCmdUI-derived class). This object represents the menu item or toolbar button or other user-interface object that generated the command. The update handler calls member functions of the CCmdUI structure through the pointer to update the user-interface object. For example, here is an update handler for the Clear All menu item:
void CMyWinApp::OnUpdateEditClearAll(CCmdUI *pCmdUI)
{
pCmdUI->Enable(m_bClearAllAvailable);
}
This handler calls the Enable member function of an object with access to the menu item. Enable makes the item available for use.