How to import type extension function in Kotlin

Question

I wrote an extension function for Any type, that will retrieve object property value by its name. I want to be able to use it from everywhere in my project. Here is my extension function:

package com.example.core.utils.validation

import java.util.NoSuchElementException
import kotlin.reflect.full.memberProperties

fun Any.getFieldValue(fieldName: String): Any? {
    try {
        return this.javaClass.kotlin.memberProperties.first { it.name == fieldName }.get(this)
    } catch (e: NoSuchElementException) {
        throw NoSuchFieldException(fieldName)
    }
}

Now I want to use it like this

package com.example.core

import com.example.core.utils.validation.*

class App {
    val obj = object {
        val field = "value"
    }

    val fieldValue = obj.getFieldValue("field")
}

But there is Unresolved reference error

How should I make my extension function global and import it anywhere?

Looks like it should work to me... Are both in a single project? — Alexey Romanov, Jul 06 '18 at 16:38

redlabrat · Accepted Answer · 2018-07-06T12:13:39.650

7

You should use import statement instead of second package declaration in your second code snippet.

See documentation: https://kotlinlang.org/docs/reference/extensions.html#scope-of-extensions

And actually I am not sure that it is valid to make extension for Any type. I think in that case you need to call it on object of type Any.

edited Jul 06 '18 at 12:13

answered Jul 06 '18 at 12:10

redlabrat

507
7
14

sorry it was a mistake in the post, not in my code. Thanks – mustafo Jul 06 '18 at 12:10
"And actually I am not sure that it is valid to make extension for Any type." Yes, it is. – Alexey Romanov Jul 06 '18 at 16:35
An example is `import okhttp3.MediaType.Companion.toMediaType` – lcapra Feb 07 '20 at 09:20

How to import type extension function in Kotlin

1 Answers1