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packages/@n8n/di/README.md

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+## @n8n/di
+
+`@n8n/di` is a dependency injection (DI) container library, based on [`typedi`](https://github.com/typestack/typedi).
+
+n8n no longer uses `typedi` because:
+
+- `typedi` is no longer officially maintained
+- Need for future-proofing, e.g. stage-3 decorators
+- Small enough that it is worth the maintenance burden
+- Easier to customize, e.g. to simplify unit tests
+
+### Usage
+
+```typescript
+// from https://github.com/typestack/typedi/blob/develop/README.md
+import { Container, Service } from 'typedi';
+
+@Service()
+class ExampleInjectedService {
+  printMessage() {
+    console.log('I am alive!');
+  }
+}
+
+@Service()
+class ExampleService {
+  constructor(
+    // because we annotated ExampleInjectedService with the @Service()
+    // decorator TypeDI will automatically inject an instance of
+    // ExampleInjectedService here when the ExampleService class is requested
+    // from TypeDI.
+    public injectedService: ExampleInjectedService
+  ) {}
+}
+
+const serviceInstance = Container.get(ExampleService);
+// we request an instance of ExampleService from TypeDI
+
+serviceInstance.injectedService.printMessage();
+// logs "I am alive!" to the console
+```
+
+Requires enabling these flags in `tsconfig.json`:
+
+```json
+{
+  "compilerOptions": {
+    "experimentalDecorators": true,
+    "emitDecoratorMetadata": true
+  }
+}
+```