Compose using an instance?

[astanciu]

I can't figure out if this is possible and if so, how.

I'd like to be able to compose using an existing POJO or previous instance. ex:

const obj = {name: 'something'}

const Thing = stampit.compose(obj, OtherStamp, etc..)

I saw there's a convert-class utility, why not a convert-object? or is there a simpler way to do this other than merging object myself?

[koresar]

Sure there is a way. Actually, three ways. :)

If your POJO props need to go the __proto__ then:

const obj = {name: 'something'}
const Thing = stampit.methods(obj).compose(OtherStamp, etc..)

If they need to be regular properties (a-la mixin) then:

const obj = {name: 'something'}
const Thing = stampit.props(obj).compose(OtherStamp, etc..)

If you want some control over assignment logic then:

const obj = {name: 'something'}
const Thing = stampit.init(function () {
  this.name = obj.name;
}).compose(OtherStamp, etc..)

---

A good idea would be to extract that stamp to a separate variable, which would have a descriptive name. For example:

const HaveNameSomething = stampit.props({name: 'something'})

const Thing = stampit(HaveNameSomething, OtherStamp, etc..)

---

Here is a 5 min article which can help you to get your head around the above code.

[astanciu]

Amazing, so simple.. thank you.

[astanciu]

Quick followup, if obj was instantiated from a Stamp, its methods are on proto, which means neither .props nor .methods will pick them up:

  const Bar = stampit.methods({
    bar() {
      console.log('bar');
    }
  });

  const obj = Bar();

  const a = stampit.props(obj)(); // a.bar() undefined
  const b = stampit.methods(obj)(); // b.bar() undefined
  const c = stampit.methods(obj.__proto__)(); // bcbar() exists

Is this recommended if you want to enhance an existing Instance: const d = stampit.props(obj).methods(obj.__proto__).compose(Something)()

[koresar]

We recommend developers to do whatever they want with they code! Stampit do not have any formal rules you should follow. So, yeah. Your code is absolutely valid and recommended. :)

Good job on reading the above mentioned article. 👍