Lambda with pure C++03

thanks to powerful generic ZFCallback, we are able to implement lambda feature with pure C++03
example:

ZFUIRect refCapture = ZFUIRectZero();
ZFUIRect valueCapture = ZFUIRectZero();
 
ZFLISTENER_2(onClick
        , ZFUIRect &, refCapture
        , ZFUIRect, valueCapture
        ) {
    refCapture.width = 999;
    valueCapture.width = 999;
} ZFLISTENER_END()
 
zfobj<ZFUIButton> btn;
btn->observerAdd(ZFUIButton::EventButtonOnClick(), onClick);
 
zfLogTrim() << "before invoke: " << refCapture << valueCapture;
btn->simulateClick();
zfLogTrim() << "after invoke: " << refCapture << valueCapture;
 
// output:
//   before invoke: (0, 0, 0, 0) (0, 0, 0, 0)
//   after invoke: (0, 0, 999, 0) (0, 0, 0, 0)

as you may noticed, we can capture vars outside of the lambda function
you should take care of the life circle of the captured vars, though