imperium

@smounters/imperium-events

Typed in-process event emitter for @smounters/imperium. Decorate methods with @OnEvent() and emit from any service. Supports wildcard patterns.

Part of the Imperium monorepo.

Install

pnpm add @smounters/imperium-events

Usage

import { Injectable, Module } from "@smounters/imperium/decorators";
import { OnEvent, EventModule, EventService } from "@smounters/imperium-events";

// --- Listener ---

@Injectable()
class TradeNotifier {
  @OnEvent("trade.opened")
  async onTradeOpened(payload: { symbol: string; price: number }) {
    // push notification, log, update stats
  }

  @OnEvent("trade.*") // wildcard — matches trade.opened, trade.closed, etc.
  async auditLog(payload: unknown) {
    // write to audit log
  }
}

// --- Emitter ---

@Injectable()
class TradingEngine {
  constructor(private readonly events: EventService) {}

  async executeTrade(symbol: string, price: number) {
    // ... execute trade logic
    await this.events.emit("trade.opened", { symbol, price });
  }
}

// --- Module ---

@Module({
  imports: [EventModule.register({ listeners: [TradeNotifier] })],
  providers: [TradingEngine],
})
class TradingModule {}

API

@OnEvent(pattern)

Method decorator. Registers the method as a handler for events matching the pattern.

• "trade.opened" — exact match
• "trade.*" — wildcard, matches any single segment

EventModule.register({ listeners })

Dynamic module. Pass providers that contain @OnEvent() methods.

EventService

Injectable service:

• emit(event, payload?) — emit an event. All matching handlers run concurrently. Errors in individual handlers are caught and logged without blocking others.
• getHandlers() — returns registered handlers (for introspection/testing)

Documentation

Full guide: smounters.github.io/imperium/guide/events

License

MIT