[Solved]Scala programm with non-understandable expression

chen_s · October 20, 2023, 10:20am

Hi all,

I am working on some project, in which we are using ota-community-edition as base. In their implementation there are a lot place using following expression e.g.

(LogDirectives.logResponseMetrics(“device-registry”) & requestMetrics(metricRegistry) & versionHeaders(version)) {
prometheusMetricsRoutes ~
tracing.traceRequests { implicit serverRequestTracing =>
new DeviceRegistryRoutes(authNamespace, namespaceAuthorizer, messageBus).route
}
} ~ DbHealthResource(versionMap, healthMetrics = Seq(new BusListenerMetrics(metricRegistry))).route

I find nowhere the meaning of ~ in such expression. And in the file the “prometheusMetricsRoutes” is not defined. I am a newbie of scala, can someone explain me this expression a bit? below is the link to the file

github.com

advancedtelematic/ota-device-registry/blob/master/src/main/scala/com/advancedtelematic/ota/deviceregistry/Boot.scala

/*
 * Copyright (C) 2017 HERE Global B.V.
 *
 * Licensed under the Mozilla Public License, version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     https://www.mozilla.org/en-US/MPL/2.0/
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * SPDX-License-Identifier: MPL-2.0
 * License-Filename: LICENSE
 */

package com.advancedtelematic.ota.deviceregistry

This file has been truncated. show original

Thanks a lot

adamdabrowski · October 20, 2023, 10:45am

It’s from Akka; take a look at the Combinators section: The PathMatcher DSL • Akka HTTP