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@michelsalib
Created April 22, 2015 15:52
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Typescript @timestampable annotation
@timestampable
class Dog {
public name: string = 'Paul';
}
function timestampable(func) {
return <any>(function() {
var genericConstructor = () => {};
genericConstructor.prototype = func.prototype;
var instance = new genericConstructor();
func.apply(instance, <any>arguments);
instance.createdAt = new Date();
(<any>Object).observe(instance, (changes) => {
if (changes.length == 1 && changes[0].name == 'updatedAt') {
return;
}
instance.updatedAt = new Date();
});
return instance;
});
}
// create my dog
var d = new Dog();
console.log(d.name, (<any>d).createdAt, (<any>d).updatedAt);
// change his name in 100ms
setTimeout(() => {
d.name = 'Pierre';
// let time for updatedAt to be computed and print next tick
setTimeout(() => {
console.log(d.name, (<any>d).createdAt, (<any>d).updatedAt);
});
}, 100);
@robertpenner
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That's really creative!

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