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https://issues.apache.org/jira/browse/FLINK-2017?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15010493#comment-15010493
]
ASF GitHub Bot commented on FLINK-2017:
---------------------------------------
Github user rmetzger commented on the pull request:
https://github.com/apache/flink/pull/1097#issuecomment-157645907
Thank you for reviewing the pull request while I was away @fhueske.
I've just tried it out with this code:
```java
RequiredParameters rp = new RequiredParameters();
rp.add("input");
rp.add("output");
rp.add(new Option("parallelism").alt("p").help("Set the parallelism for all
operators").type(OptionType.INTEGER));
ParameterTool pt = ParameterTool.fromArgs(args);
try {
rp.applyTo(pt);
} catch(RequiredParametersException rpe) {
System.out.println(rp.getHelp());
System.exit(1);
}
```
and the output is the following:
```
Required Parameter
name, short name, help text, default valueinput null
output null
parallelism p Set the parallelism for all operators
```
I think the `getHelp` method is not producing helpful output here.
How about something like:
```
Required Parameters:
--input
--output
-p, --parallelism Set the parallelism for all operators
```
The `RequiredParametersException` could list the missing arguments.
> 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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