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https://issues.apache.org/jira/browse/FLINK-2017?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14967409#comment-14967409
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ASF GitHub Bot commented on FLINK-2017:
---------------------------------------
Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/1097#discussion_r42648726
--- Diff:
flink-java/src/main/java/org/apache/flink/api/java/utils/RequiredParameter.java
---
@@ -0,0 +1,149 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache 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
+ *
+ * http://www.apache.org/licenses/LICENSE-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.
+ */
+
+package org.apache.flink.api.java.utils;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Objects;
+
+/**
+ * Facility to manage required parameters in user defined functions.
+ */
+public class RequiredParameter {
+
+ private static final String HELP_TEXT_PARAM_DELIMITER = "\t";
+ private static final String HELP_TEXT_LINE_DELIMITER = "\n";
+
+ private HashMap<String, Option> data;
+
+ public RequiredParameter() {
+ this.data = new HashMap<>();
+ }
+
+ public void add(Option option) throws RequiredParameterException {
--- End diff --
Why not changing the signature of this method to `public Option add(String
name)`?
This would relieve the user to instantiate the Option object.
> Add predefined required parameters to ParameterTool
> ---------------------------------------------------
>
> Key: FLINK-2017
> URL: https://issues.apache.org/jira/browse/FLINK-2017
> Project: Flink
> Issue Type: Improvement
> Affects Versions: 0.9
> Reporter: Robert Metzger
> Labels: starter
>
> In FLINK-1525 we've added the {{ParameterTool}}.
> During the PR review, there was a request for required parameters.
> This issue is about implementing a facility to define required parameters.
> The tool should also be able to print a help menu with a list of all
> parameters.
> This test case shows my initial ideas how to design the API
> {code}
> @Test
> public void requiredParameters() {
> RequiredParameters required = new RequiredParameters();
> Option input = required.add("input").alt("i").help("Path to
> input file or directory"); // parameter with long and short variant
> required.add("output"); // parameter only with long variant
> Option parallelism =
> required.add("parallelism").alt("p").type(Integer.class); // parameter with
> type
> Option spOption =
> required.add("sourceParallelism").alt("sp").defaultValue(12).help("Number
> specifying the number of parallel data source instances"); // parameter with
> default value, specifying the type.
> Option executionType =
> required.add("executionType").alt("et").defaultValue("pipelined").choices("pipelined",
> "batch");
> ParameterUtil parameter = ParameterUtil.fromArgs(new
> String[]{"-i", "someinput", "--output", "someout", "-p", "15"});
> required.check(parameter);
> required.printHelp();
> required.checkAndPopulate(parameter);
> String inputString = input.get();
> int par = parallelism.getInteger();
> String output = parameter.get("output");
> int sourcePar = parameter.getInteger(spOption.getName());
> }
> {code}
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