Emit a named val in DSL2

[multimeric]

I like to name all my outputs. However, if you are outputting a simple value, it is seemingly impossible to assign a name to it in DSL2.

If I try to use emit:

nextflow.enable.dsl=2

process test {
    output:
        val "abc", emit x
    script:
        """
        true
        """
}

workflow {
    result = test()
    result.x.view()
}

No such variable: emit

If I try to re-assign a new variable:

nextflow.enable.dsl=2

process test {
    output:
        val x
    script:
        x = "abc"
        """
        true
        """
}

workflow {
    result = test()
    result.x.view()
}

Missing process or function with name 'view'

(because this isn't a named input, so only result.view() would work)

And of course I can't use into:

nextflow.enable.dsl=2

process test {
    output:
        val "abc" into x
    script:
        """
        true
        """
}

workflow {
    result = test()
    result.x.view()
}

Process clause `into` should not be provided when using DSL 2

How can this be done?

[phue]

The syntax requires to put a colon after the emit keyword, i.e:

nextflow.enable.dsl=2

process test {
    output:
        val "abc", emit: x
    script:
        """
        true
        """
}

workflow {
    test()
    test.out.x.view()
}

[phue]

Now that's odd, the above snippet works for me with nextflow 21.04.0

[multimeric]

Ah no you are right, that only happened when I forgot to enable DSL2.

[bobamess]

I see you've also corrected the other error. The original code had test.x.view(), which is why it continued to fail, but now has the correct test.out.x.view() but this was not commented on.

[multimeric]

No, my original code had result.x.view(), which is equivalent to test.out.x.view().

[bobamess]

Sorry. You're right, of course, so it did. @phue made the change to test.out.x.view() without commenting and I overlooked the result = test() bit in your original.