https://github.com/gciatto/dummy-kt-jpype

https://github.com/gciatto/dummy-kt-jpype

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• Host: GitHub
• URL: https://github.com/gciatto/dummy-kt-jpype
• Owner: gciatto
• Created: 2021-09-05T12:29:44.000Z (over 3 years ago)
• Default Branch: master
• Last Pushed: 2023-12-05T08:48:06.000Z (about 1 year ago)
• Last Synced: 2024-10-23T07:50:51.451Z (3 months ago)
• Language: Kotlin
• Size: 62.5 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 1
• Metadata Files:
  • Readme: README.md

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README

        
# Dummy project for assessing Kotlin-Python interoperability via JPype 

## Problem (Hypothesis)

Kotlin-generated nested anonymous objects do not work as expected.

Consider the following Java code creating a lazy int range generator

```java

package dummy.kt.jpype;

import java.util.Iterator;

public class IterablesJava {

    public static Iterable intRange(int min, int max) {

        return new Iterable() {

            @Override

            public Iterator iterator() {

                return new Iterator() {

                    private int x = min;

                    @Override

                    public boolean hasNext() {

                        return x < max;

                    }

                    @Override

                    public Integer next() {

                        return x++;

                    }

                };

            }

        };

    }

}

```

and its Kotlin equivalent:

```kotlin

// file named Iterables.kt => Java class is named IterablesKt

package dummy.kt.jpype

fun intRange(min: Int, max: Int): Iterable =

    object : Iterable {

        override fun iterator(): Iterator =

            object : Iterator {

                private var x = min

                override fun hasNext(): Boolean = x < max

                override fun next(): Int = x++

            }

    }

```

Then, the following Python script using both `intRange` methods from Python:

```python

import jpype

import jpype.imports

import jpype

import jpype.imports

# starting jvm

from dummy.kt.jpype import IterablesJava, IterablesKt

iterable = IterablesJava.intRange(1, 10) # works (calling the Java version)

iterator = iterable.iterator() # works

print(iterator.next()) # 1

iterable = IterablesKt.intRange(1, 10) # works (calling the Python version)

iterator = iterable.iterator() # AttributeError: 'java.lang.Object$Anonymous' object has no attribute 'iterator'

print(iterator.next()) # not executed

```

fails when executing the Kotlin version of `intRange`.

By inspecting the code, I'd say that JPype is struggling in correctly managing nested anonymous objects when the corresponding code is generated by Kotlin.

By inspecting the bytecode, I also note that the object returned by `iterable.iterator()` should not be of type `java.lang.Object$Anonymous` -- as reported by the exception message --, but rather `IterablesKt$intRange$1$iterator$1` (I guess).

### How to reproduce

1. Re-compile the JVM code by `./gradlew shadowJar`

    - This should create a fat jar containing both the Java- and Kotlin-based implementations of `intRange` in `build/libs`

        + First run make take a while since Gradle and dependencies should be downloaded

2. Restore Python dependencies via `pip install -r requirements.txt`

3. Run the `main.py` script via `python main.py`