在派生类中使用基本方法的目的

Question

I'm looking at someone's code and has:

protected override void OnMouseEnter(MouseEventArgs e)
{
    base.OnMouseEnter(e);  //necessary?
    if (...)
}

Now, question is why base class method is called? this code would work without that anyway. any idea?

Thanks. Amit

Answer 1

The base calls are used when you want to utilize the functionality of the base's implementation yet want to extend what happens in the derived classes implementation.

This can do some really useful things like setting up properties that are defined in the base class or handling events without having to put boilerplate code in each derived class.

Answer 2

由于基类方法具有默认行为，您可能仍要利用它。

Answer 3

Depending on the base class it might be necessary to also execute its method for it to function as intended. It's pretty much convention to call the base code as well as it might be important, especially if you do not know what it does.

Answer 4

It heavily depends on what you what the event handler to do. If your base class is complicated and it does a lot of things in OnMouseEnter() that you still want to keep, then you should have that base.OnMouseEnter(e) call. If you want to "override" the function completely, meaning you know what base.OnMouseEnter(e) does and you don't want it, then don't call base.OnMouseEnter(e) .