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cherrypick/cherrypick_annotations/README.md
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# cherrypick_annotations
[![License](https://img.shields.io/badge/license-Apache%202.0-blue.svg)](LICENSE)
A lightweight set of Dart annotations designed for dependency injection (DI) frameworks and code generation, inspired by modern approaches like Dagger and Injectable. Works best in tandem with [`cherrypick_generator`](https://pub.dev/packages/cherrypick_generator).
---
## Features
- **@module** Marks a class as a DI module for service/provider registration.
- **@singleton** Declares that a method or class should be provided as a singleton.
- **@instance** Marks a method or class so that a new instance is provided on each request (not a singleton).
- **@provide** Marks a method whose return value should be registered as a provider, supporting dependency injection into parameters.
- **@named** Assigns a string name to a binding for keyed resolution.
- **@params** Indicates that a parameter should be injected with runtime-supplied arguments.
These annotations streamline DI configuration and serve as markers for code generation tools such as [`cherrypick_generator`](https://pub.dev/packages/cherrypick_generator).
---
## Getting Started
### 1. Add dependency
```yaml
dependencies:
cherrypick_annotations: ^latest
```
Add as a `dev_dependency` for code generation:
```yaml
dev_dependencies:
build_runner: ^latest
cherrypick_generator:
```
### 2. Annotate your DI modules and providers
```dart
import 'package:cherrypick_annotations/cherrypick_annotations.dart';
import 'package:cherrypick/cherrypick.dart';
@module()
abstract class AppModule extends Module {
@singleton()
Dio dio() => Dio();
@named('baseUrl')
String baseUrl() => 'https://api.example.com';
@instance()
Foo foo() => Foo();
@provide()
Bar bar(Foo foo) => Bar(foo);
@provide()
String greet(@params() dynamic params) => 'Hello $params';
}
```
When used with `cherrypick_generator`, code similar to the following will be generated:
```dart
final class $AppModule extends AppModule {
@override
void builder(Scope currentScope) {
bind<Dio>().toProvide(() => dio()).singleton();
bind<String>().toProvide(() => baseUrl()).withName('baseUrl');
bind<Foo>().toInstance(foo());
bind<Bar>().toProvide(() => bar(currentScope.resolve<Foo>()));
bind<String>().toProvideWithParams((args) => greet(args));
}
}
```
---
## Annotation Reference
### `@module`
```dart
@module()
abstract class AppModule extends Module {}
```
Use on classes to mark them as a DI module. This is the root for registering your dependency providers.
---
### `@singleton`
```dart
@singleton()
Dio dio() => Dio();
```
Use on methods or classes to provide a singleton instance (the same instance is reused).
---
### `@instance`
```dart
@instance()
Foo foo() => Foo();
```
Use on methods or classes to provide a new instance on each request (not a singleton).
---
### `@provide`
```dart
@provide()
Bar bar(Foo foo) => Bar(foo);
```
Use on methods to indicate they provide a dependency to the DI module. Dependencies listed as parameters (e.g., `foo`) are resolved and injected.
---
### `@named`
```dart
@named('token')
String token() => 'abc';
```
Assigns a name to a binding for keyed injection or resolution.
---
### `@params`
```dart
@provide()
String greet(@params() dynamic params) => 'Hello $params';
```
Use on method parameters to indicate that this parameter should receive runtime-supplied arguments during dependency resolution (for example, via `.toProvide*((params) => greate(params))` in generated code).
---
## License
Licensed under the [Apache License 2.0](LICENSE).
---
## Contributing
Pull requests and feedback are welcome!
---
## Author
Sergey Penkovsky (<sergey.penkovsky@gmail.com>)