An event with multiple senders

Question

How to create an event of clicking on ANY of four buttons, i.e. avoid pasting same code into each button's OnClick event? The only thing I found in Google is that there is (?) a pattern (Multicast) for it. If it really exists, could you please provide me some examples, if not, could you make (a draft of) one?

Answer 1

You can assign the same handler to all four button OnClick events. The event's Sender parameter will tell you which button is triggering the event each time. For example:

void __fastcall TMyForm::ButtonClick(TObject *Sender)
{
    TButton *btn = static_cast<TButton*>(Sender);
    ShowMessage("You clicked on " + btn->Name);
}

If your code needs to behave depending on which button is clicked, you can use the Tag property to differentiate, for example:

void __fastcall TMyForm::ButtonClick(TObject *Sender)
{
    TButton *btn = static_cast<TButton*>(Sender);
    switch (btn->Tag)
    {
        ...
    }
}

Answer 2

Assuming that the Button1->OnClick have been assigned :

Button2->OnClick = Button1->OnClick
Button3->OnClick = Button1->OnClick
Button4->OnClick = Button1->OnClick