`Args` design

[bvssvni]

Notice: This design is not used!

This design is inspired by Windows.Forms in C#, but made more powerful by using Rust's enum type. The idea is to separate the arguments from the enum declaration of the event.

pub enum InputEvent {
    KeyPress(KeyPressArgs),
    KeyRelease(KeyReleaseArgs),
    MousePress(MousePressArgs),
    MouseRelease(MouseReleaseArgs),
    ...
}

• It makes it easy to extend event arguments without breaking existing code
• Define custom collections of events

The arguments has a precise semantics. For example, the MouseMoveArgs contains the mouse position.

[bvssvni]

One drawback with this design is that it does not allow matching against any button press in a single statement.

[tomaka]

Instead of using this, I would suggest using the struct_variant feature instead.

For example:

#![feature(struct_variant)]

pub enum Event {
    KeyPress {
        pub key: int,
        pub something: int,
    },

    KeyRelease {
        pub key: int,
        pub something: int,
    },
}

fn foo(ev: &Event) {
    match ev {
        &KeyPress{ref key, ..} => (),
        &KeyRelease{ref something, ..} => (),
    }
}