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Traits in ES6 now
/*
var Trait1 = {
method1() {}
};
var Trait2 = {
method2() {}
};
var Trait3 = mixin({
method3() {}
}, Trait2);
hasTrait(Trait3, Trait2) // true
hasTrait(Trait3, Trait1) // false
class Base {}
class Foo extends mixinClass(Base, Trait1) {}
hasTrait(Foo, Trait1) // true
hasTrait(Foo, Trait2) // false
class Foo2 extends Foo {}
hasTrait(Foo2, Trait1) // true
hasTrait(Foo2, Trait2) // false
class Foo3 extends mixinClass(Foo, Trait2) {}
hasTrait(Foo3, Trait1) // true
hasTrait(Foo3, Trait2) // true
class Bar extends mixinClass(Base, Trait3) {}
hasTrait(Bar, Trait1) // false
hasTrait(Bar, Trait2) // true
hasTrait(Bar, Trait3) // true
*/
// Mixin traits into an Object (another trait)
export function mixin(object, ...traits) {
let _traits = [];
if (object._traits) {
Array.prototype.push.apply(_traits, object._traits);
}
let props = {
_traits: {
value: _traits,
writable: true,
configurable: true
}
};
for (let trait of traits) {
if (trait._traits) {
Array.prototype.push.apply(_traits, trait._traits);
}
for (let name of Object.getOwnPropertyNames(trait)) {
if (name !== "_traits" && ! object.hasOwnProperty(name)) {
props[name] = {
value: trait[name],
writable: true,
configurable: true
};
}
}
_traits.push(trait);
}
Object.defineProperties(object, props);
return object;
}
// Mixin traits into a class. class Foo extends mixinClass(Base, Trait1) {}
export function mixinClass(baseClass, ...traits) {
class traitedClass extends baseClass {};
mixin.apply(this, [traitedClass.prototype].concat(traits));
return traitedClass;
}
// Checks to see if a class or trait has a trait
export function hasTrait(object, trait) {
let _traits;
if (typeof object === "function") {
_traits = object.prototype._traits;
} else {
_traits = object._traits;
}
return Array.isArray(_traits) && _traits.indexOf(trait) >= 0;
}
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