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https://issues.apache.org/jira/browse/GROOVY-9599?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17141605#comment-17141605
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Remko Popma commented on GROOVY-9599:
-------------------------------------
This turned out to have a separate, very different cause from GROOVY-9519.
Given code like this:
{code:java}
def cli = new CliBuilder()
cli.s(type: String, longOpt: 'str', required: false, args: 1, defaultValue: '',
'description')
{code}
the {{groovy.cli.picocli.CliBuilder}} class constructs a
{{picocli.CommandLine.Model.OptionSpec}} from the method arguments.
These method arguments are given to the conversion logic as a {{Map<String,
Object>}}. During this conversion, there is the following conditional that
prevents all options from getting an empty String value as their default value:
{code:java}
// Map m
if (!m.defaultValue) { //<-- (line 943) BAD: evaluates to false if value is
empty String.
m.remove('defaultValue') // don't default the picocli model to empty string
}
{code}
This works fine when no default is specified, or when the default is specified
as something that does not evaluate to {{false}} as per Groovy Truthiness, but
when an empty String is intentionally specified as the default, what actually
happens is that the default value becomes {{null}}.
The correct code should just look at the absence or presence of the
"defaultValue" key in the map:
{code:java}
if (!m.containsKey('defaultValue')) { // GROOVY-9599
m.remove('defaultValue') // don't default the picocli model to empty string
}
{code}
I will commit a fix and an additional test soon.
> CliBuilder: Option with "type: String, defaultValue ''" (empty String)
> results in NullObject if default value is applied
> ------------------------------------------------------------------------------------------------------------------------
>
> Key: GROOVY-9599
> URL: https://issues.apache.org/jira/browse/GROOVY-9599
> Project: Groovy
> Issue Type: Bug
> Components: command line processing
> Affects Versions: 3.0.4
> Reporter: Remko Popma
> Assignee: Remko Popma
> Priority: Major
> Fix For: 3.0.5
>
>
> This is a follow-up ticket for GROOVY-9519:
> After checking with Groovy 3.0.4, it seems that only the "Integer with
> defaultValue '0'" case was fixed, but not "String with defaultValue ''". The
> latter became even worse. It still ignores the defaultValue, but instead of
> creating a Boolean, it now creates a NullObject. Try this code:
> {code:java}
> @Grab('info.picocli:picocli-groovy:4.3.2')
> @GrabConfig(systemClassLoader=true)
> import groovy.cli.picocli.CliBuilder
> def cli = new CliBuilder(name: 'cliTest.groovy', stopAtNonOption: false)
> cli.h(type: Boolean, longOpt: 'help', usageHelp: true, required: false, 'Show
> usage information')
> cli.a(type: String, longOpt: 'optA', required: false, args: 1, defaultValue:
> '', 'Option a (optional)')
> def opts = cli.parse(args)
> opts || System.exit(1)
> if(opts.h) {
> cli.usage()
> System.exit(0)
> }
> println(opts.a.getClass())
> if (opts.a) {
> println(opts.a)
> }
> {code}
> with Groovy 3.0.2:
> {code:java}
> % ~/tmp/groovy-3.0.2/bin/groovy ./cliTest.groovy
> class java.lang.Boolean
> {code}
> and with Groovy 3.0.4:
> {code:java}
> % ~/tmp/groovy-3.0.4/bin/groovy ./cliTest.groovy
> class org.codehaus.groovy.runtime.NullObject
> {code}
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