Building a custom observable type

Question

Hello guys.

I'm looking at this quickstart http://msdn.microsoft.com/en-us/library/windows/apps/hh700355.aspx and I'm trying to reuse it in my code. So, I've added the following definitions:

var DadosBase = WinJS.Class.define(
            function (nome, morada) {
                this.nome = nome;
                this.morada = morada;                
            });


var DadosObs = WinJS.Class.mix(DadosBase,
        WinJS.Binding.mixin,
        WinJS.Binding.expandProperties(DadosBase));

Now, the problem: this won't work at runtime because _backingData isn't initialized. After taking a peek at the code, it seems like I'm supposed to call _initObservable from my constructor (the quickstart doesn't even mentions the method). Now, that being the case, I really see no advantages on creating bindable types instead of creating non-bindable types and passing them to the as method.

Comments?

---

Luis Abreu

Answer 1

Hello guys.

This is an old thread, but I see that there are still no comments on this. 

Any comments?

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Luis Abreu

Answer 2

Ok, a couple of minuts more and I've got the code working. I've ended up with this code:

var DadosObs = WinJS.Class.mix(function (nome, morada) {
        var interno = new DadosBase(nome, morada);
        this._initObservable(interno);
        Object.defineProperties(this, WinJS.Binding.expandProperties(interno));
        },
        WinJS.Binding.mixin
    ); 

btw, I've noticed that this will also work:

var DadosObs = WinJS.Class.mix(function (nome, morada) {
        var interno = new DadosBase(nome, morada);
        this._initObservable(interno);
       );
        },
        WinJS.Binding.mixin,
        WinJS.Binding.expandProperties(new DadosBase("", "") )    
); 

Now, I'm not sure if this is the correct way to do this, but it does work...Now, can someone from MS comment on the code shown here http://msdn.microsoft.com/en-us/library/windows/apps/hh700355.aspx:

WinJS.Class.mix(Person,
    WinJS.Binding.mixin,
    WinJS.Binding.expandProperties(Person)
); 

It has nothing to do with the final version I've written. Is it wrong? if it is, why is it still online?

thanks.

---

Luis Abreu

Answer 3

putting this back on top :)

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Luis Abreu

Answer 4

Can anyone  answer this please?

thanks.

---

Luis Abreu