Template methods

template-methods.ts

abstract class AbstractAggregationClient {
  constructor(private readonly options) {}

  //
  // Public interface
  //

  public getAccounts(params): AggregationResult {
    try {
      // Preparation step
      this.beforeAggregation(params);
      // Actual execution
      return this.getAccountsImpl(params);
    } catch (e) {
      // Error handling
      return this.onError(params, e);
    } finally {
      // Cleanup step
      this.afterAggregation(params);
    }
  }

  //
  // Template methods
  //

  protected getAccountsImpl(params): AggregationResult {
    // Let the child classes override this method
  }

  protected beforeAggregation(params): void {
    // Do something. Child classes can override this method
  }

  protected afterAggregation(params): void {
    // Do something. Child classes can override this method
  }

  protected onError(params, error): AggregationResult {
    // Default error handling. Child classes can override this method
    this.logger.error(error);
  }
}