Create GObject trait and move connect method to there

[osa1]

Resolves #118.

All examples are working.

There's also another way of handling this. We can have something like this:

pub trait Signals<S:Signal> {
    fn connect(&self, &s: S);
}

and implement this for every type. I think this is a bit better because it allows us to have more precise types, for example, we can't connect a callback to a signal that the object won't fire. If you like this idea I think I can implement.

[osa1]

To clarify the alternative approach, here's a concrete example. GtkTreeView doesn't signal Clicked but we can still connect a Clicked handler to it. Using this trait-based approach, we can prevent this by not implementing Signals<Clicked> for TreeView.

The problem with this approach is that we'll need to implement huge amounts of trait implementations. Maybe current approach is better for simplicity.

[jeremyletang]

Hey, the current code is correct for me.

I think too, the second approach will be better. Just one thing, I think that Connect will be more appropriate instead of Signals for the trait name.

A simple macro will allow us to generate the implementation easily.

Just a simple example for the macro:

#![feature(macro_rules)]

struct Widget;
struct Clicked;
struct Pressed;
struct NotSignal;

pub trait Signal {}
impl Signal for Clicked {}
impl Signal for Pressed {}

pub trait Connect<S> {
    fn connect(&self, s: &S);
}

macro_rules! impl_connect(
    ($struct_name:ident -> $($signal_name:ident),*) => (
        $(impl Connect<$signal_name> for $struct_name {
            fn connect(&self, s: &$signal_name) {
                println!("signal connected !");
            }
        })*
    );
)

impl_connect!(Widget -> Clicked, Pressed)

Just tells me what you want to do !

[osa1]

You're right that we can use macros to make the job a lot easier.

Still, I say let's merge this for now, and work on refactoring like that later. We can open an issue to keep track of progress on implementing trait-based approach.

(The problem is that I need to work on my application and I don't want to spend a lot of time on bindings for now, as long as it provides me functions I need ..)

[jeremyletang]

Okay no problem! so il will work on this tonight if I have time. Just by curiosity you're application is open source / on github ?

[osa1]

Thanks.

My app is not open source yet, but it'll eventually be open source.