Options in subcommands are not reset to their initial value

[remkop]

When a single CommandLine instance is reused multiple times, picocli is supposed to reset the values of all options and positional parameters to their initial value, and then to their default value (if a default value was defined in the annotations).

Scope

With picocli 4.2.0, subcommand options are not cleared between invocations. This impacts applications that reuse a CommandLine instance in multiple invocations. If an option was specified in the first invocation and omitted in the second invocation, it will incorrectly retain the value from the first invocation.

The problem does not manifest when a subcommand is invoked only once in a JVM process. Also, applications that do not reuse a CommandLine instance, and applications without subcommands, are not impacted.

The problem was introduced in version 4.2.0 and does not exist in picocli 4.1.4 and earlier.

Workaround

This regression does not apply to options that have a defaultValue defined in the annotation: options defined as @Option(... defaultValue="...") will correctly be reset to the default value in between multiple invocations. Use the defaultValue annotation where possible.

Cause

The cause is related to recent changes for lazy subcommand instantiation and repeatable subcommands.

private TypedMember(Field field, IScope scope) {
    this(field);
    if (ObjectScope.isProxyClass(scope)) {
        throw new InitializationException("Invalid picocli annotation on interface field");
    }
    FieldBinding binding = new FieldBinding(scope, field);
    getter = binding; setter = binding;
    this.scope = scope;
    hasInitialValue &= ObjectScope.hasInstance(scope); // <--- used to be obj != null
}

I may be possible to fix this by implementing this idea:
#961 (similar to #962)

[remkop]

Fixed in master.

To verify, 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!