dedup_list.py

import sys
from collections import OrderedDict


class DedupList(list):
    def __init__(self, seq=()):
        # print("init")
        dic = {} if sys.version_info[1] > 5 else OrderedDict()
        seq = list(dic.fromkeys(seq))
        self._dedup_set = set(seq)
        super().__init__(seq)

    def __setitem__(self, key, value):
        # print(f"setitem - {key} - {value}")
        self._dedup_set.remove(self[key])
        # if value not in self._dedup_set:  # this breaks item swap
        self._dedup_set.add(value)
        super().__setitem__(key, value)

    def append(self, obj):
        # print(f"append - {obj}")
        if obj not in self._dedup_set:
            self._dedup_set.add(obj)
            super().append(obj)

    def extend(self, iterable):
        # print(f"extend - {iterable}")
        for object in iterable:
            if object not in self._dedup_set:
                self._dedup_set.add(object)
                super().append(object)

    def insert(self, index: int, obj):
        # print(f"insert - {index} - {obj}")
        if obj not in self._dedup_set:
            self._dedup_set.add(obj)
            super().insert(index, obj)

    def pop(self, index: int = None):
        # print(f"pop - {index}")
        index = index if index else -1
        item = super().pop(index)
        self._dedup_set.remove(item)
        return item