Function main

examples/context/src/context-observation.ts:42–86

()

}

export async function main() {
  const appCtx = new Context('app');
  const requestCtx = new RequestContext(appCtx, 'request');

  // Observer events from `appCtx`
  appCtx.subscribe({
    filter: filterByTag('greeter'),
    observe: (eventType, binding) => {
      console.log('[observer] %s %s', eventType, binding.key);
    },
  });

  // Create a context view on `requestCtx`
  const greetersView = requestCtx.createView(filterByKey(/^greeters\./));
  greetersView.on('refresh', () => {
    console.log(
      '[view.refresh] %j',
      greetersView.bindings.map(b => b.key),
    );
  });

  // Add EnglishGreeter to `appCtx`
  console.log('Adding EnglishGreeter');
  appCtx.bind('greeters.EnglishGreeter').toClass(EnglishGreeter).tag('greeter');

  // Add ChineseGreeter to `appCtx`
  await setImmediateAsync();
  console.log('Adding ChineseGreeter');
  appCtx.bind('greeters.ChineseGreeter').toClass(ChineseGreeter).tag('greeter');

  // Remove ChineseGreeter from `appCtx`
  await setImmediateAsync();
  console.log('Removing ChineseGreeter');
  appCtx.unbind('greeters.ChineseGreeter');

  // Add ChineseGreeter to `requestCtx`
  await setImmediateAsync();
  console.log('Adding ChineseGreeter to request context');
  requestCtx
    .bind('greeters.ChineseGreeter')
    .toClass(ChineseGreeter)
    .tag('greeter');

  await requestCtx.waitUntilObserversNotified();
}

if (require.main === module) {
  main().catch(err => {