[jira] [Commented] (FLINK-2017) Add predefined required parameters to ParameterTool

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-2017?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14967409#comment-14967409 ] 

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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