behavior of defaultValue

[sjyMystery]

Hi, guys:
There's an unexpected behavior of the defaultValue param in @Option Annotation.
When use default values from environment variables of invalid types, it always throws ParameterException even though I passed the value of the argument.

How to solve it

Maybe we can disable the type-checking of default value when the argument value has been already passed.

And I will be honored to submit the example code of this situation and create a pull request if necessary.

[remkop]

Can you please show how to reproduce this problem?

[sjyMystery]

Of course, the code is below:

import picocli.CommandLine;

@CommandLine.Command(name = "run")
public class App implements Runnable {

    @CommandLine.Option(names = "--port", defaultValue = "${env:PORT}", required = true)
    Integer PORT;


    static public void main(String[] args) {
        App app = new App();
        args = new String[]{"--port", "5672"};
        CommandLine cmd = new CommandLine(app);
        cmd.execute(args);
    }

    public void run() {
        System.out.println(PORT);

    }
}

before run :

export PORT="xxx"

[sjyMystery]

then may below information in stderr:

Invalid value for option '--port': 'xxx' is not an int
Usage: run [--port=PORT>]
      --port=<PORT>

[remkop]

@sjyMystery Thank you for the clarification. I understand the issue now.
It looks like this is the same cause as this ticket: #961 (I just changed the title of that ticket.)

Please read my comment on that ticket for more details.

Are you interested in providing a pull request for this? That would be great!

[sjyMystery]

@remkop I've get your point.By the way, is there anything need or suggested to read before I make a pr?Thanks.

[remkop]

@sjyMystery There is no documentation on the implementation, just the source code. :-)

It may be as simple as reordering these 2 lines in CommandLine$Interpreter.parse(List, Stack, String[], List) on line 11486:

Before:

private void parse(List<CommandLine> parsedCommands, Stack<String> argumentStack, String[] originalArgs, List<Object> nowProcessing) {
...
  try {
    applyDefaultValues(required); // currently defaults are applied first
    processArguments(parsedCommands, argumentStack, required, initialized, originalArgs, nowProcessing);
  } catch (InitializationException ex) {
...

After:

private void parse(List<CommandLine> parsedCommands, Stack<String> argumentStack, String[] originalArgs, List<Object> nowProcessing) {
...
  try {
    processArguments(parsedCommands, argumentStack, required, initialized, originalArgs, nowProcessing);
    applyDefaultValues(required, initialized);  // only apply defaults to the missing args
  } catch (InitializationException ex) {
...

Then, in applyDefaultValues(), we only modify the ArgSpec objects that are not in the initialized set.

But let's add some tests to verify.

[remkop]

@sjyMystery Have you had a chance to look at this? Let me know if you get stuck anywhere, I will try to help. :-)

[remkop]

Fixed in master.

To verify this, check out picocli master locally, and build it with publishToMavenLocal. That should publish picocli-4.2.1-SNAPSHOT to your local .m2 Maven cache.

git clone https://github.com/remkop/picocli.git
cd picocli
gradlew publishToMavenLocal

You can then try this in a project that uses the info.picocli:picocli:4.2.1-SNAPSHOT dependency. Feedback very welcome!