Isolated

Scope-modifier decorator. Marks a provider as isolated, ensuring a unique instance of the provider is created for each associated context.

Useful for scenarios where the same provider class must yield distinct instances based on different contexts.

⚠️

Only one scope-modifier can be applied to a provider class. Multiple scope-modifier will result in a MultipleScopeModifierError.

import {
  application,
  Context,
  contextualize,
  isolated,
  provide,
  provider
} from 'aspectra'
import { randomUUID } from 'node:crypto'
 
@isolated
@provider
class Logger {
  public readonly id = randomUUID()
}
 
@contextualize('database', Context.global)
@provider
class Database {
  @provide(Logger)
  public readonly logger!: Logger // First instance
}
 
@contextualize('printer', Context.global)
@provider
class Printer {
  @provide(Logger)
  public readonly logger!: Logger // New instance
}
 
@contextualize('printer', Context.global)
@provider
class OtherPrinter {
  @provide(Logger)
  public readonly logger!: Logger // Same instance as `Printer`
}
 
@application
class Application {
  @provide(Database)
  private readonly database!: Database
 
  @provide(Printer)
  private readonly printer!: Printer
 
  @provide(OtherPrinter)
  private readonly otherPrinter!: OtherPrinter
 
  public start() {
    console.table({
      database: this.database.logger.id,
      printer: this.printer.logger.id,
      otherPrinter: this.otherPrinter.logger.id
    })
  }
}

[auto-generated] output:

┌──────────────┬────────────────────────────────────────┐
│ (index)      │ Values                                 │
├──────────────┼────────────────────────────────────────┤
│ database     │ '0e1758dc-fbf0-4666-8a9b-181bf5d98e48' │
│ printer      │ '4e23936f-1b9e-437a-a2eb-0709aac2ada2' │
│ otherPrinter │ '4e23936f-1b9e-437a-a2eb-0709aac2ada2' │
└──────────────┴────────────────────────────────────────┘