How to amend two levels by also introduce local properties at the first level

[StefMa]

Wow, sorry for the title 🙈

Given I have a template like this:

module Jobber

jobs: Listing<Job>

Now I have two files that amends it:

amends "modules/Jobber.pkl"

jobs {
 job1 {}
 job2 {}
 job3 {}
 job4 {}
}

amends "modules/Jobber.pkl"

jobs {
 job1 {}
 job2 {}
 job3 {
  // Does something different than the other child
 }
 job4 {}
}

So basically, file b is identical to file a, except of a single job.

I thought I can extract a BaseJobber that amends Jobber and have somekind of customJobs: Listing<Job>.
My BaseJobber could look like that:

amends "modules/Jobber.pkl"

customJobs: Listing<Job>

jobs {
 job1 {}
 job2 {}
 ...customJobs
 job4 {}
}

And the childs can amends BaseJobber and only override customJobs with their custom jobs.

But this doesn't work. I can't introduce new properties when I amend a module.

In my current solution I use import Jobber in my BaseJobber and define defaults.
Plus a function like

function jobs(injectedJob: Listing<Job>): Listing<Job> = new {
 job1 {}
 job2 {}
 ...customJobs
 job4 {}
}

With that the child can call amends the Jobber and import the BaseJobber and basically delegating everything to it.
This works, but doesn't look correct 🫠
What is the pkl way to go to handle this case? 🤔
Thanks in advance!

[bioball]

There's multiple ways to skin the cat!

One pattern is to define another module that sets its output to the underlying module's output. It can then expose customJobs like you were thinking:

// Jobber.pkl

module Jobber

jobs: Listing<Job>

class Job { name: String }

// fancyJobber.pkl

import "Jobber.pkl"

customJobs: Listing<Jobber.Job>

fixed jobber: Jobber = new {
  jobs {
    new { name = "job 1" }
    new { name = "job 2" }
    ...customJobs
    new { name = "job 3" }
    new { name = "job 4" }
  }
}

output = jobber.output

// myFancyJobber.pkl

amends "fancyJobber.pkl"

customJobs {
  new { name = "my custom job" }
}

[StefMa]

Thaks for the answer @bioball!
My example was a bit too simplified.
My Jobber has multiple properties.

If we introduce a name: String there, the whole thing doesn't work anymore.
Or at least I don't know how to.

I tried the following, but this don't work.
Of course, the output of fancyJobber is defined as a Listing.

// Jobber.pkl

module Jobber

jobs: Listing<Job>

class Job { name: String }

name: String

// fancyJobber.pkl

import "Jobber.pkl"

customName: String
fixed name: String = "Fancy Jobber"

customJobs: Listing<Jobber.Job>
fixed jobber: Jobber = new {
    jobs {
        new { name = "job 1" }
        new { name = "job 2" }
        ...customJobs
        new { name = "job 3" }
        new { name = "job 4" }
    }
}

output = jobber.output

// myFancyJobber.pkl

amends "fancyJobber.pkl"

customName = "My Fancy Jobber"

customJobs {
    new { name = "my custom job" }
}

When running eval on the myFancyJobber.pkl

pkl eval somewhere/modules/myFancyJobber.pkl

–– Pkl Error ––
Tried to read property `name` but its value is undefined.

7 | name: String
    ^^^^
at Jobber#name (file:///somewhere/modules/Jobber.pkl, line 7)

The above error occurred when rendering path `name`.

106 | text = renderer.renderDocument(value)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
at pkl.base#Module.output.text (https://github.com/apple/pkl/blob/0.26.3/stdlib/base.pkl#L106)