provider-launcher v1.0.1

provider-launcher

Usage

Suppose we have three providers A, B, C. The dependency graph as follows:

A <- B <- C

It means we should launch them in order: A, B, C, and shutdown them after use in order: C, B, A.

Let's implement all of them in typescript:

class A implements Provider {
  static readonly dependencies = [];

  // Do asynchronous initialization after construction.
  async initialize() {}

  // Finalize resources.
  async finalize() {}
}

class B implements Provider {
  static readonly dependencies = [A];

  // An initialized instance of A will be injected.
  constructor(a: A) {}

  async initialize() {}

  async finalize() {}
}

class C implements Provider {
  // Since A is an indirect dependency of C, it can be omitted.
  static readonly dependencies = [B];

  // An initialized instance of B will be injected.
  constructor(b: B) {}

  async initialize() {}

  async finalize() {}
}

Now we can launch them and aquire an instance of C:

const launcher = new ProviderLauncher(A, B, C);
await launcher.initialize();
const c = launcher.get(C);
// Do whatever you want with c.
// ......
await launcher.finalize();

Practical Example

For practical example, please check example folder. To run example, just type npm run example.