Dependency manager

This lib provides a simplistic dependency manager.

Features

Resolves dependencies only when they are needed
Detects circular dependency
Strong type support

The previous major release used to allow asynchronous dependencies and the use of class as identifier, but those features were replaced by the Symbol identifier to keep the lib dead simple.

Basic usage

import { DependencyManager } from 'dependency-manager/mod.ts'

// 1. Create a manager:
const manager = new DependencyManager();

// 2. Create a dependency (a provider and an identifier):
const value = 'foo';
const provider = () => value;
const identifier = Symbol() as DependencyIdentifier<typeof value>;

// 3. Register the dependency:
manager.register(identifier, provider);

// 4. Anywhere in your code, inject the resolved dependency value:
const value = await manager.inject(identifier);

Identifier

An identifier is a uniq value used by the dependency manager to store and retrieve the dependency.

The DependencyIdentifier type allow the return value of the inject method to be fully typed,

Providers

A dependency is rarely just a simple value like in the basic usage code and often rely on other dependencies.

That's why the register method takes a function (that we call the dependency provider) who's role is to build the dependency.

That function receive a uniq parameter: The dependency manager. That way it is possible to inject dependencies inside it:

function providerA() {
  return 'foo'
}
const identifierA = Symbol() as DependencyIdentifier<ReturnType<typeof providerA>>;

function providerB(manager: DependencyManager) {
  const a = manager.inject(identifierA);
  return `The value is: ${a}`;
}
const identifierB = Symbol() as DependencyIdentifier<ReturnType<typeof providerB>>;

manager.register(identifierA, providerA);
manager.register(identifierB, providerB);

// ...

const b = manager.inject(identifierB); // "The value is: foo"

Errors

The register method throw an error if:

the dependency is already registred.

The inject method throw an error if:

the dependency is not registred.
a circular dependency is detected

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