René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"MRO conflict on Set and Comparable","articleBody":"I'm trying to use custom class implementing Set and Comparable interface in Jython but have the following error : \n`Exception in thread \"main\" TypeError: Supertypes that share a modified attribute have an MRO conflict[attribute=__le__, supertypes=[\u003ctype 'java.util.Set'\u003e], type=Scratch$MyCollection]`\n\nI am using java temurin 21.0.6 and jython-standalone 2.7.4.\n\nI prepared a simple code example to reproduce : \n\n```java\n    public static void main(String[] args) {\n        try (PythonInterpreter interpreter = new PythonInterpreter()) {\n            interpreter.set(\"c\", new MyCollection());\n        }\n    }\n```\n(Please note that you can just use `Py.java2py(new MyCollection())` and will achieve the same result)\n\nWhere MyCollection is a basic implementation :\n\n```java\n    private static class MyCollection implements Set, Comparable {\n        @Override\n        public int compareTo(@NotNull Object o) {\n            return 0;\n        }\n\n        @Override\n        public int size() {\n            return 0;\n        }\n\n        @Override\n        public boolean isEmpty() {\n            return false;\n        }\n\n        @Override\n        public boolean contains(Object o) {\n            return false;\n        }\n\n        @Override\n        public @NotNull Iterator iterator() {\n            return null;\n        }\n\n        @Override\n        public @NotNull Object[] toArray() {\n            return new Object[0];\n        }\n\n        @Override\n        public boolean add(Object o) {\n            return false;\n        }\n\n        @Override\n        public boolean remove(Object o) {\n            return false;\n        }\n\n        @Override\n        public boolean addAll(@NotNull Collection c) {\n            return false;\n        }\n\n        @Override\n        public void clear() {\n\n        }\n\n        @Override\n        public boolean removeAll(@NotNull Collection c) {\n            return false;\n        }\n\n        @Override\n        public boolean retainAll(@NotNull Collection c) {\n            return false;\n        }\n\n        @Override\n        public boolean containsAll(@NotNull Collection c) {\n            return false;\n        }\n\n        @Override\n        public @NotNull Object[] toArray(@NotNull Object[] a) {\n            return new Object[0];\n        }\n    }\n```\n\nAlso, I tried in previous version 2.7.3 to 2.7.0 this even simpler code and has a similar error yet not the same :\n\n```java\n    public static void main(String[] args) {\n        try (PythonInterpreter interpreter = new PythonInterpreter()) {\n            interpreter.set(\"c\", new TreeSet\u003c\u003e());\n        }\n    }\n```\n\n`Exception in thread \"main\" TypeError: Supertypes that share a modified attribute have an MRO conflict[attribute=remove, supertypes=[\u003ctype 'java.util.SequencedSet'\u003e, \u003ctype 'java.util.Set'\u003e], type=SortedSet]`\n\nI tried to look a bit into it but failed to grasp exactly what is wrong, I feel like the PyJavaType.bases field is the key here, it's an array and from what I see, the order of the element inside it determine if the MRO will crash or not.","author":{"url":"https://github.com/bomboleo","@type":"Person","name":"bomboleo"},"datePublished":"2025-07-16T12:34:25.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":1},"url":"https://github.com/391/jython/issues/391"}