Prototype of generating copyDynamic extension functions for data classes, such that you can do this:

@CopyDynamic
data class Foo(val bar: String = "bar", val baz: String = "baz", val fizz: String = "fizz")

And have a copyDynamic extension function generated to allow for dynamic setting of variables in a copy call.

val foo = Foo()

val newFoo = foo.copyDynamic {
  bar = "newBar"
  if (someCondition) baz = "newBaz"
}

Configuration

You can optionally specify a copydynamic.generated annotation processing option with a value of either "javax.annotation.processing.Generated" (JDK 9+) or "javax.annotation.Generated" (JDK <9).

Incremental annotation processing is disabled by default (as Kapt doesn't formally support this when generating Kotlin sources currently). This does appear to work in Android projects though with Kotlin 1.3.30+. If you want to try this, you can enable it via copdynamic.useFiler.

kapt {
  arguments {
    arg("copydynamic.generated", "javax.annotation.Generated")
    arg("copydynamic.useFiler", "true")
  }
}

Caveats

• The generated intermediate builder has internal visibility for its constructor, which can be considered a bit of a leaky API. If you use this, it's recommended to put your models in a separate module to avoid leaking this.
• Properties must be internal or public visibility.

kapt 'io.sweers.copydynamic:copydynamic:x.y.z'
compileOnly 'io.sweers.copydynamic:copydynamic-annotations:x.y.z'

KDocs can be found here: https://zacsweers.github.io/copydynamic

Copyright (C) 2018 Zac Sweers

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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