68 lines
2.0 KiB
Markdown
68 lines
2.0 KiB
Markdown
# Dependency manager
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This lib provides a simplistic dependency manager.
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## Features
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- Resolves dependencies only when they are needed
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- Detect circular dependency
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- Accept any valid `Map` key as dependency identifier
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- Infer the dependency type from the dependency identifier if the later is a class
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## Usage
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1. Create a manager:
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```typescript
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import { DependencyManager } from 'dependency-manager/mod.ts'
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const manager = new DependencyManager()
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```
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2. Register dependencies by giving the manager an identifier and a provider:
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```typescript
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manager.register('dependency-identifier', () => 'value');
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```
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3. Get the dependency by giving the manager its identifier (always asynchrone):
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```typescript
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const value = await manager.resolve('dependency-identifier');
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```
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## Providers
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Providers are functions that are called when resolving the dependency for the first time.
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They receive the dependency manager as parameter, and should return the dependency value, or a promise that resolves to it.
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Example of the registration of a dependency which provider uses another dependency:
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```typescript
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async function provider(manager: DependencyManager) {
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const value = await manager.resolve('dependencyIdentifier');
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return `The value is: ${valueA}`;
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}
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manager.register('other-identifier', provider);
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```
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## Identifiers and typing
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Any valid `Map` key can be used as identifier, but using a class allow the return value of the `resolve` method to be automatically typed:
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```typescript
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class MyDependency {}
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const a = await manager.resolve(MyDependecy); //< `a` is of type `MyDependency`
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const b = await manager.resolve('dependency-identifier'); //< `b` is of type `unknown`
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const c = await manager.resolve<number>('dependency-identifier'); //< `c` is of type `number`
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```
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## Errors
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The `register` method throw an error if:
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- the name is already used.
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The `resolve` method throw an error if:
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- the name doesn't exist (if no module has been registred with the given name).
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- a circular dependency is detected |