talentcomposer

The talentcomposer is a tool which can compose pieces of capabilities (talents) with each other and also talents with an instance. This tool can help you to do role oriented programming. The implementation is based on the publication of the Software Composition Group part of the Institute of Computer Science (INF) at the University of Bern

Supported engines

node v8 and v10

Notes

1. The package mainliner utilizes this package.
2. Conflict resolution between talents is explicit. The programmer has to resolve conflicts using either the alias or the exclude method. See below in the examples
3. Conflict resolution between an instance and talents is implicit. The member will delegated on to the instance blindly. If there is already a member on the instance with same name it's gonna be shadowed or overridden.
4. Although the publication allows stateful talents I would NOT not recommend to use them with this tool. Like DON'T do this (It's leaking anyway)

const Composer = require("talentcomposer");
let x = 0;
 
module.export = Composer.createTalent({
  method() {
 
    x += 1;
 
    return x;
  }
});

Examples

Composing an instance with talents

const assert = require("assert");
const Composer = require("talentcomposer");
 
class Person {
  constructor(name) {
    this.name = name;
  }
  eating() {}
  sleeping() {}
}
 
const studentTalent = Composer.createTalent({
  studying() {}
});
 
const teacherTalent = Composer.createTalent({
  teaching() {}
});
 
const sportTalent = Composer.createTalent({
  swimming() {}
});
 
let travis = new Person("Travis");
let mavis = new Person("Mavis");
 
travis = Composer.composeWithTalents(travis, studentTalent, sportTalent);
mavis = Composer.composeWithTalents(mavis, teacherTalent, sportTalent);
 
assert.ok(travis.studying);
assert.ok(travis.swimming);
assert.ok(mavis.teaching);
assert.ok(mavis.swimming);

Composing talents

const assert = require("assert");
const Composer = require("talentcomposer");
 
const circusTalent = Composer.createTalent({
  juggling() {},
  clowning() {}
});
 
const sportTalent = Composer.createTalent({
  running() {},
  swimming() {}
});
 
combinedTalents = Composer.composeTalents(circusTalent, sportTalent);
 
assert.ok(combinedTalents.juggling);
assert.deepEqual(combinedTalents.juggling, circusTalent.juggling);
assert.ok(combinedTalents.clowning);
assert.deepEqual(combinedTalents.clowning, circusTalent.clowning);
assert.ok(combinedTalents.running);
assert.deepEqual(combinedTalents.running, sportTalent.running);
assert.ok(combinedTalents.swimming);
assert.deepEqual(combinedTalents.swimming, sportTalent.swimming);

Require an unimplemented capability

const assert = require("assert");
const Composer = require("talentcomposer");
 
class Person {
  constructor(name) {
    this.name = name;
  }
  eating() {}
  sleeping() {}
}
 
const courierTalent = Composer.createTalent({
  "cycling": Composer.required,
  delivering() {
    this.cycling();
  }
});
 
const sportTalent = Composer.createTalent({
  cycling() {}
});
 
let travis = new Person("Travis");
 
travis = Composer.composeWithTalents(travis, courierTalent, sportTalent);
 
assert.ok(travis.cycling);
assert.deepEqual(travis.cycling, sportTalent.cycling);
assert.ok(travis.delivering);
assert.deepEqual(travis.delivering, courierTalent.delivering);

Require an unimplemented capability on the prototype of a class

const assert = require("assert");
const Composer = require("talentcomposer");
 
class Person {
  constructor(name) {
    this.name = name;
  }
  get drawing() {
    return Composer.required;
  }
  eating() {}
  sleeping() {}
}
 
const artTalent = Composer.createTalent({
  drawing() {}
});
 
let travis = new Person("Travis");
 
travis = Composer.composeWithTalents(travis, artTalent);
 
assert.ok(travis.drawing);
assert.deepEqual(travis.drawing, artTalent.drawing);

Require an unimplemented capability in the constructor of a class

const assert = require("assert");
const Composer = require("talentcomposer");
 
class Person {
  constructor(name) {
    this.name = name;
    this.painting = Composer.required;
  }
  eating() {}
  sleeping() {}
}
 
const artTalent = Composer.createTalent({
  painting() {}
});
 
let travis = new Person("Travis");
 
travis = Composer.composeWithTalents(travis, artTalent);
 
assert.ok(travis.painting);
assert.deepEqual(travis.painting, artTalent.painting);

Explicit conflict resolution (aliasing)

const assert = require("assert");
const Composer = require("talentcomposer");
 
const courierTalent = Composer.createTalent({
  cycling() {console.log("like a courier");}
});
 
const sportTalent = Composer.createTalent({
  cycling() {console.log("like an athlete");}
});
 
combinedTalents = Composer.composeTalents(
    courierTalent,
    Composer.alias(sportTalent, "cycling", "riding")
);
 
assert.ok(combinedTalents.cycling);
assert.deepEqual(combinedTalents.cycling, courierTalent.cycling);
assert.ok(combinedTalents.riding);
assert.deepEqual(combinedTalents.riding, sportTalent.cycling);

Explicit conflict resolution (excluding)

const assert = require("assert");
const Composer = require("talentcomposer");
 
const courierTalent = Composer.createTalent({
  cycling() {console.log("like a courier");},
  delivering() {}
});
 
const sportTalent = Composer.createTalent({
  cycling() {console.log("like a athlete");},
  swimming() {}
});
 
combinedTalents = Composer.composeTalents(
    courierTalent,
    Composer.exclude(sportTalent, "cycling")
);
 
assert.ok(combinedTalents.cycling);
assert.deepEqual(combinedTalents.cycling, courierTalent.cycling);
assert.ok(combinedTalents.cycling);
assert.deepEqual(combinedTalents.cycling, courierTalent.cycling);
assert.ok(combinedTalents.delivering);
assert.deepEqual(combinedTalents.delivering, courierTalent.delivering);

API

createTalent(record: Object): Talent

Creates a new talent

composeWithTalents(instance: Object, ...talents: Talent[]): Object

Composes talents with an instantiated object

composeTalents(...talents: Talent[]): Talent

Composes talents into one

alias(talent: Talent, methodName: string, alias: string): Talent

Aliases a method of the talent (It doesn't mutate the talent but returns a new one)

exclude(talent: Talent, methodName: string): Talent

Excludes a method of the talent (It doesn't mutate the talent but returns a new one)

required: Symbol

Property to mark required members for talents