website/docs/guide/walkthrough/dependency-injection.md

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:::warning This contains version 2 code. Please view transitioning to v3 :::

Since version 2.0.0, dependency injection, thanks to iti, is a feature to customize your bot's utilities and structures.

Minimal setup for any project.

const client = new Client({
    ...options
})
Sern.makeDependencies<MyDependencies>({
    build: root => 
        root.add({ 
            '@sern/client': single(() => client)
        })
})

For any typescript project, you'll need to add an interface to get intellisense and typings.

interface MyDependencies extends Dependencies {
    '@sern/client': Singleton<Client>
}

Full Dependency Injection setup

const client = new Client({
    ...options
})

interface MyDependencies extends Dependencies {
    '@sern/client': Singleton<Client>
}

export const useContainer = Sern.makeDependencies<MyDependencies>({
    build: root => 
        root.add({ 
            '@sern/client': single(() => client)
        })
})

Everything else is handled. However, you may want customize things.

Adding dependencies to root

Each sern built dependency must implement its contracts.

• @sern/logger: Log data. Logging
• @sern/errors: Handling errors and lifetime. ErrorHandling
• @sern/modules: Managing all command modules. ModuleManager
• @sern/emitter: is the key to emit events and occurences in a project. SernEmitter

You may also add disposers so that when the application crashes, the targeted dependency calls that function.

export const useContainer = Sern.makeDependencies<MyDependencies>({
   build: root => 
       root.add({ 
           '@sern/client': single(() => client)
       })
       .addDisposer({ '@sern/client': client => client.destroy() })
})

:::tip Below is v3 api. :::

Init

Do you need to perform intializing behavor for a dependency?

import { Init } from '@sern/handler'; 
class Database implements Init {
    init() {
        await this.connect()
        console.log('Connected');
    }
}

Modify you Dependencies interface:

import type { Initializable } from '@sern/handler'

interface Dependencies extends CoreDependencies {
    database: Initializable<Database>
}

Make sure its been added:

await makeDependencies({ 
    build: root => root 
        .add({ database => new Database() })
})