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Re: Virtual functions versus callbacks [message #24213 is a reply to message #24202]

Tue, 05 January 2010 17:55

mrjt
Messages: 705
Registered: March 2007
Location: London

Contributor

There are two additional options you missed out:

3- Catch unhandled key presses in the Ctrls owner/parent. ie:

virtual void Key(dword key, int count)
{
    if (key == K_RETURN && password_field.HasFocus())
       login.PseudoPush();
    else
       return false;
    return true;
}

Since you'd have to declare a new function to handle a callback anyway this isn't really any extra code.

4- Create a simple template to automate callback functionality:

template <class T>
struct WithCallbacks : public T {
   Callback WhenLeftDown

   virtual void LeftDown(Point p, dword keyflags) { WhenLeftDown(); }
}
...
WithCallbacks<ArrayCtrl> array;

Given all the possible methods it doesn't seem worth retro-actively adding callbacks everywhere.

OTOH, the K_RETURN event for EditField is common enough to warrant it's addition. It should be called WhenReturn or maybe WhenKeyReturn to match the key enum though. WhenEnter is too easy to confuse with the focus changing IMO.

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