Re: [Vala] Tryout adding simple support for extension methods to valac

[Luca Bruno <lethalman88 gmail com>]

On 14/10/2013 17:56, Philip Van Hoof wrote:
> Hi there,
>
> Attached you can find a tryout for adding simple support for extension
> methods to valac.
>
> I'm nonetheless mailing this unfinished work to the mailing list for
> feedback already. Especially how I'm finding the Class to add the method
> to concerns me (I dislike the find_in_tree which I added to Namespace).
>
> I'm also unsure about just using add_method on the class, instead of
> adding a add_extension_method instead (and keeping the list separate).
> That or perhaps have a is_extension bool on Vala.Method?
>
> Right now the compiler will not use the parameter's identifier to refer
> to the this object. Instead only 'this' works. The Code writer must I
> guess also do something like TestA *a = this at the top of the function?
>
> The syntax that I'm aiming for is very much like extension methods in
> C#:
>
> public class Test {
>         public void Existing() {
>         }
> }
>
> public void Method (this Test a) {
>         // a.Existing(); doesn't work yet
>         this.Existing(); // works atm, but should use a here
> }
>
> Hoping for input and assistance from more experience Valac developers ;-)

Thanks for your contribution :-)
A couple of points:
1) Patches/feature requests go to bugzilla, unless you want them to be 
forgotten and eaten by the darkness :) IIRC there's already a bug about 
that.
2) Instead of defining methods without a class scope and 
special-casing/altering the syntax of parameters, I'd suggest either:

extend class Test {
    public void method () { }
}

which adds a namespacing and makes the method look like more an instance 
method in its usage and definition.

or:

[Extend]
public void method (Test this) {
}