FWS. S2E2. Property order.

Fun With Stamps. Season 2 — Best practices. Episode 2 — Property order.

Hello. I’m developer Vasyl Boroviak and welcome to the second season, second episode of Vasyl Boroviak presents Fun with Stamps.

In this season of FWS mini-articles we are going to learn stamp Best Practices using the stampit npm module.

What’s the best ordering of the stamp parts?

TL;DR: order elements in the sequence of its execution.

Let’s start from an example. Please, read the comments.

The behaviouristic-utility stamp below counts the number of objects created from the stamp you compose it with.

// Firstly, other stamps/composables you want to mix with.
const HasInstanceCounter = stampit(SomeStamp, AnotherStamp, {
  // Then give it a runtime name.
  name: "HasInstanceCounter",
  // This line executed while this .js file is parsed and loaded.
  conf: {
    instanceCounter: 0
  },
  // This function is executed during composition, i.e.
  // during HasInstanceCounter stamp creation.
  composers({ stamp }) {
    stamp.compose.configuration.instanceCounter = 0
  },
props: {
    // This property will be assigned to object instance right
    // before the initialiser below.
    instanceIndex: -1
  },
  // This is called during object creation.
  init(_, { stamp }) {
    this.instanceIndex = stamp.compose.configuration.instanceCounter
    stamp.compose.configuration.instanceCounter += 1
  },
methods: {
    // Executed whenever you call this method.
    getInstanceNumber() {
      return this.instanceIndex
    }
  },
statics: {
    // Call it when you need to know a total number of instances,
    // MyStamp.getNumberOfInstances()
    getNumberOfInstances() {
      return this.compose.configuration.instanceCounter
    }
  }
});

Let’s shorten this down to the ordered list:

• stamps you want to mix with (see above SomeStamp, AnotherStamp)
• name
• configuration (rarely used feature)
• composers (rarely used feature)
• properties
• initializers
• methods
• statics (first — data properties, then — methods)

The rest of the episodes:

• Season one
• S2E1. Naming stamps
• S2E2. Property order (this article)