Unbinding a lambda event handler

Question

How can I unbind an event handler which I've bind as shown below?

MyFrame::MyFrame()
{
    Bind(wxEVT_COMMAND_MENU_SELECTED,
         [](wxCommandEvent&) {
            // Do something useful
         },

         wxID_EXIT);
}

Many thanks for the first answer. I've added some additional information.

The possibility to unbind an event handler by using a concrete Functor is documented and works fine, but if you use the C++ 11 lambda style to bind somthing, later there is no Functor availibale to call the unbind method. And this causes trouble if the corresponding wxEvtHandler should by destroied.

Is there a "trick". . . if not I don't see a real use case to bind by using lambda functors. Hopefully I'm wrong . . .

Many thanks
Hacki

Answer 1

You can't unbind when the call to Bind has a lambda, as your example. If you store the lambda, then you can unbind from that, e.g.

class MyFrame 
{ 
    ... 
    std::function<void()> DoUnbind;
}

MyFrame::MyFrame()
{
    auto DoSomethingUseful = [](wxCommandEvent&) {
            // Do something useful
         };

    Bind(wxEVT_COMMAND_MENU_SELECTED,
         DoSomethingUseful,
         wxID_EXIT);

    DoUnbind = [DoSomethingUseful](){
        Unbind(wxEVT_COMMAND_MENU_SELECTED,
               DoSomethingUseful,
               wxID_EXIT);
    };
}