Is it possible to define a ReactJS Mixin method that can be overridden in a React Component?

Question

The Facebook ReactJS library has strict rules about which component methods can be overridden and how. Unless it's specifically allowed, we cannot redefine a method.

For my custom mixins how can I update the SpecPolicy if I have a method I want to allow to be overridden? Is this even possible?

This example is a bit contrived but it should get the point across. Say I have the mixin below which is trying to provide a default renderItem method, intended to be overridden if necessary. When I attempt to render the component <Hello ... /> I get an Invariant Violation error. You can find a jsfiddle here.

var MyMixin = {
    render: function () {
        return this.renderItem();
    },
    renderItem: function () {
        return <div>Hello {this.props.name}</div>;
    }
};

var Hello = React.createClass({
    mixins: [MyMixin],
    renderItem: function() {
        return <div>Hey {this.props.name}</div>;
    }
});

Answer 1

This isn't possible right now. It's likely that a future version of React will have mixins that take advantage of ES6 classes and will be a bit more flexible. See here for a proposal:

https://github.com/reactjs/react-future/blob/master/01%20-%20Core/02%20-%20Mixins.js