objectmakr

ObjectMakr

An abstract factory for dynamic attribute-based classes.

Usage

ObjectMakr lazily creates classes based on inheritance trees with additional properties. You can then make new instances of those classes at runtime.

The system works almost identically to traditional classes that extend each other, with the added benefit of lazy instantiation from plain old JavaScript objects.

Constructor

import { ObjectMakr } from "objectmakr";

const objectMaker = new ObjectMakr({
    inheritance: {
        Solid: {
            Block: {},
        },
    },
    properties: {
        Block: {
            photo: "Question Mark",
        },
        Solid: {
            size: 8,
        },
    },
});

const block = objectMaker.make("Block");

block.photo; // "Question Mark"
block.size; // 8

inheritance

A tree representing class inheritances, where keys are class names. The sub-objects under each class name key are classes inheriting from that class.

The root object is always Object, as with normal JavaScript classes.

properties

Flat mapping of class names to any properties added to that class' prototype.

indexMap

How properties can be mapped from an array to indices on created members. If this is passed in, class properties will be allowed to be specified as arrays.

const objectMaker = new ObjectMakr({
    indexMap: ["photo", "contents"],
    inheritance: {
        Solid: {
            Block: ["Question Mark", "Coin"],
            Brick: ["Bricks"],
        },
    },
    properties: {
        Block: ["Question Mark"],
        Solid: {
            size: 8,
        },
    },
});

const block = objectMaker.make("Block");

block.photo; // "Question Mark"
block.contents; // "Coin"

const brick = objectMaker.make("Brick");

brick.photo; // "Bricks"
brick.contents; // undefined

onMake

Member name for a function on instances to be called upon creation. If this is provided, any class instance with a member under this name will call that member as a function when made with make.

The function is called with the member as its scope, and takes in the member and the class name.

const calledOnMake = console.log.bind(console, "Creating:");
const objectMaker = new ObjectMakr({
    inheritance: {
        Solid: {
            Block: {},
        },
    },
    onMake: "creator",
    properties: {
        Solid: {
            creator: calledOnMake,
        },
    },
});

// Creating: class_1 {} Block
objectMaker.make("Block");

make

Creates a new instance of a class. If the class doesn't yet exist in-memory, it's created based on its inheritance and properties.

const block = objectMaker.make("Block");

block.photo; // "Question Mark"
block.size; // 8

make also accepts an additional settings parameter with any settings overrides to be shallow-copied onto the object.

const bigBlock = objectMaker.make("Block", {
    size: 16,
});

block.photo; // "Question Mark"
bigBlock.size; // 16

Development

After forking the repo from GitHub:

git clone https://github.com/<your-name-here>/ObjectMakr
cd ObjectMakr
npm install
npm run setup
npm run verify

• npm run setup creates a few auto-generated setup files locally.
• npm run verify builds, lints, and runs tests.

Building

npm run watch

Source files are written under src/ in TypeScript and compile in-place to JavaScript files. npm run watch will directly run the TypeScript compiler on source files in watch mode. Use it in the background while developing to keep the compiled files up-to-date.

Running Tests

npm run test

Test files are alongside source files under src/ and named *.test.ts?. Whenever you add, remove, or rename a *.test.ts? file under src/, re-run npm run test:setup to regenerate the list of static test files in test/index.html. You can open that file in a browser to debug through the tests. npm run test will run that setup and execute tests using Puppeteer.