extension-kid
v0.2.4
Published
π©βπ¬ Please be aware that this package is still experimental β changes to the interface and underlying implementation are likely, and future development or maintenance is not guaranteed.
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Extension Kid πΆ
π©βπ¬ Please be aware that this package is still experimental β changes to the interface and underlying implementation are likely, and future development or maintenance is not guaranteed.
Acknowledgments
The Framework is based and heavily inspired by the internal package system used in Theia IDE. Precisely @theia/core package version v0.3.7. The version was distributed under Apache 2.0 license.
Expected knowledge
Developer is expected to have prior knowledge of inversify.js and Dependency Injection pattern.
Key Concepts
The framework provides a way of modularizing applications. It brings two key concepts: Service
and Extension
.
Service
Service represents a place of your app you'd like to have extendable. Service has a named ExtensionProvider
and expects its extensions to implement a certain interface.
export const MyServiceExtension = Symbol("MyServiceExtension");
export interface IMyServiceExtension {
// ...
}
@injectable
export class MyService {
constructor(
@inject(ExtensionProvider)
@named(MyServiceExtension)
extensionProvider: ExtensionProvider
) {
this._extensionProvider = extensionProvider;
}
}
The Framework comes with one service Application
.
Extension
Piece of code that implements interface of a specific Service
export class MyExtension implements IMyServiceExtension {
// ...
}
Extensions are meant to be bound to an ExtensionProvider
.
ExtensionProvider
Extension provider holds references to a container and a service identifier. The purpose of the provider is to fetch extensions from the container named after the service identifier.
Unless you need a very specific behavior from an extension provider you are highly encouraged to use the provided implementation. Otherwise you're free to implement your own provider.
To bind an extension provider to a service identifier use bindExtensionProvider
helper:
new ContainerModule(bind => {
bindExtensionProvider(bind, MyServiceExtension);
});
then you can simply bind extensions to the provider:
new ContainerModule(bind => {
bind(MyServiceExtension).to(MyExtension1);
bind(MyServiceExtension).to(MyExtension2);
});
Container
Extends inversify.js Container
and wraps EventEmitter
. The container emits events on every bind
, unbind
and rebind
method calls.
ExtensionProvider
uses this feature to expose observable interface, so that your service can be notified every time a new extension is being bound to the container.
Packages
Package resolver (TBD)
There's no package resolver mechanism in place yet.
Authoring a package
Typical package consists of one or several Extensions
.
The default export of a package should be a factory function that accepts one argument context
and returns a ContainerModule.
export default _context => {
return new ContainerModule(bind => {
// Do all the bindings you need here
});
};
context
argument is optional and will be used by the resolver (TBD) to parameterize the package. There's no more information currently, we just would like to establish the interface so that nobody will have to adjust their packages in the future.
Loading packages into your application
As there's no resolver yet, you should figure out the way of loading all your packages either at compile time or runtime or both.
At compile time in your application's composition root you can import packages and load them into a container.
import extensionFramework, { Container } from "extension-kid";
import packageFactory from "your-package";
const container = new Container();
container.load(extensionsFramework);
const package = packageFactory();
container.load(package);
export default container;