gistfile1.js

var FooModel = Y.Base.create('fooModel', Y.Model, [], {
    idAttribute : 'uid'
}, {
    ATTRS : {
        uid : {}
        foo : {}
    }
});

var foo = new FooModel({ uid: '1', foo: 'foo' });
foo.get('id') === '1'   // => true
foo.get('uid') === '1'  // => false? it became `undefined`

// calling `attrHost.get()` ends up calling `attrHost.set()` under the hood.
// we change the behavior of `set` operations to keep `id` and a custom idAttribute in sync.
// with our fix to `_getAttrInitVal`:

foo.get('id') === foo.get('uid')    // => true

// and the order these are `get`-ed doesn't matter:

foo.get('uid') === foo.get('id')    // => true