I have created several DSL frameworks in Kotlin before, and often came to situations where I wanted ...

# language-proposals

[vngantk]

I have created several DSL frameworks in Kotlin before, and often came to situations where I wanted to overload the assignment “=” operator. I know the reason why the Kotlin team is so reluctant to provide this feature because it could be greatly misused. Can I suggest an alternative? Instead of “=”, Kotlin provides a new operator called “:=“, which has no intrinsic meaning unless you explicitly define an operator function for it. The name of this operator function can be called “assign” or “colonAssign”.

[ephemient]

https://github.com/Kotlin/KEEP/issues/309

[ephemient]

https://plugins.gradle.org/plugin/org.jetbrains.kotlin.plugin.assignment

[vngantk]

I have tried the plugin. I doesn’t work. Any more information on how to use it?

[ephemient]

from the command-line,

package fqdn

annotation class SupportsKotlinAssignmentOverloading

@SupportsKotlinAssignmentOverloading
class Settable<T>(var value: T)

fun <T> Settable<T>.assign(value: T) {
    this.value = value
}

$KOTLIN_HOME/bin/kotlinc-jvm -Xplugin=$KOTLIN_HOME/lib/assignment-compiler-plugin.jar -P plugin:org.jetbrains.kotlin.assignment:annotation=fqdn.SupportsKotlinAssignmentOverloading ...

(you can see all the strings in https://github.com/JetBrains/kotlin/blob/master/plugins/assign-plugin/assign-plugin.common/src/org/jetbrains/kotlin/assignment/plugin/AssignmentPluginNames.kt)

[ephemient]

there is be a Gradle extension too, https://github.com/JetBrains/kotlin/blob/master/libraries/tools/kotlin-assignment/src/common/kotlin/org/jetbrains/kotlin/assignment/plugin/gradle/AssignmentExtension.kt

[asdf asdf]

Agree with this a lot, there's been several times w/ DSLs where I find it to be useful to overload =. The assignment plugin seems cool, but I couldn't find a lot of documentation on how to use it

[elizarov]

@asdf asdf It would be great if you add use-cases with your DSLs to the KEEP.

[Adam S]

https://kotlinlang.slack.com/archives/CQ3GFJTU1/p1681569791861459?thread_ts=1681564006.929359&cid=CQ3GFJTU1