micronaut-projects/micronaut-core

Scala Support: Add a scala compiler plugin

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#675 opened on Oct 3, 2018

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 (7 comments) (61 reactions) (0 assignees)Java (5,882 stars) (1,025 forks)batch import
help wantedtype: enhancement

Description

Scala doesn't currently support Java's Annotation Processing API, instead they have a compiler plugin API.

The Micronaut team has no Scala experts as committers, this issue is here to track the fact this is a desired feature, that we are currently looking help for from the Scala community to implement.

For reference Groovy doesn't support APT either, only Kotlin and Java do. The Groovy implementation can be found at:

The Java/Kotlin implementation at:

Any takers?

Contributor guide

Tech stack
scalajavakotlingroovy
Domain
backend
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
5
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
over 1 week
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Scala compiler plugin APIMicronaut AST transforms
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20
Research direction
Study the existing Groovy implementation at inject groovy/src/main/groovy/io/micronaut/ast/groovy/InjectTransform.groovy and the Java/Kotlin implementation at inject java/src/main/java/io/micronaut/annotation/processing/BeanDefinitionInjectProcessor.java. Understand how they intercept compilation to generate bean definitions. Then design a Scala compiler plugin that replicates this functionality using the Scala compiler plugin API. The issue lacks Scala expertise among maintainers, so focus on leveraging the existing AST transform pattern and adapting it to Scala's plugin model.