staged Builder for Factories

[bmarwell]

Hi,

I'd love to see https://immutables.github.io/factory.html supporting a staged builder.

Caveat: in #761 you argued that external builders and staged builders combined make no sense. Please do look at the last comment. I think this can be implemented (for both Factory and Immutables).

[dsinghvi]

+1 this would be great for my use case

[dsinghvi]

@elucash would you accept a contribution?

[bmarwell]

@elucash would you consider this? There is even @dsinghvi who would contribute.

[bmarwell]

Hi @elucash any chance on this?

[elucash]

Hi @bmarwell I'll look into this (i.e. what can we do). Wanted to carve a day to work on Immutables, which seems like today :)

[bmarwell]

Woohooo 🎉
Let me know if I can help (eg docs or writing a test).

[elucash]

I would definitely ask for help with documentation/guide. But as of now I'm quite puzzled how to change builder generation for factory (digging our code and trying to restore the picture) from top level to nested, we cannot put stage interfaces inside builder as it's prohibited for a type to extend/implement the type nested inside it (while the other way around is not a problem)

[elucash]

Experimental implementation PR, need more testing, more changes than expected. The solution requires now to have @Value.Enclosing annotation in the class with factories, otherwise it's quite difficult to arrange proper generation.

@Value.Enclosing
@Value.Style(stagedBuilder = true)
public class StagedFactory {
	@Builder.Factory
	public static String superstring(int theory, String reality, @Nullable Void evidence) {
		return theory + " != " + reality + ", " + evidence;
	}
}

  // generates the following methods/interfaces
  ImmutableStagedFactory.SuperstringTheoryBuildStage a = ImmutableStagedFactory.superstringBuilder();
  ImmutableStagedFactory.SuperstringRealityBuildStage b = a.theory(1);
  ImmutableStagedFactory.SuperstringBuildFinal c = b.reality("x");
  ImmutableStagedFactory.SuperstringBuildFinal d = c.evidence(null);
  String superstring = d.build();

Immutable* pattern for enclosing generated class can be changed using Style.typeImmutableEnclosing

will get back to it in a couple of days, need a fresh look

[bmarwell]

Hey! Thanks, will take a look at it in a few days (or maybe after vacation). Thank you so much for getting started! 👍🏻

[bmarwell]

Hey @elucash, I cannot compile your branch :(

[ERROR] $HOME/git/immutables/mirror/target/generated-sources/annotations/org/immutables/mirror/processor/Generator_Mirrors.java:[238,93] error: ';' expected

[elucash]

Hm.. I'm doing mvn clean install and it works for me and for CI https://github.com/immutables/immutables/actions/runs/3699719352/jobs/6267370633
I appreciate If anyone chime in and help to understand what the problem is. I'm not saying there's no problem, but I cannot reproduce one with a clean checkout. (Maybe Windows specific stuff, not a clean checkout, build cache of some sort?

[bmarwell]

Will try again!

[bmarwell]

Is 5eb1de3 on any version in central I can try?

[elucash]

Probably, 2.10.0-rc0 contains this already

[bmarwell]

Will try, sorry for the delay

[bmarwell]

Hey @elucash!

tested with 2.10.0.

The annotated Constructor of "MyObject" will result in a compile error in the return line:

    public void build() {
      checkRequiredAttributes();
      return MyObject.<init>(str1, s2, s3);
    }

// and last method in class MyObjectBuildFinal

    /* Builds a new {@link void !should_not_be_used_in_generated_code!}. */
    void build();

[bmarwell]

The Factory builder works flawlessly, thanks! :)