Class ObservableList

src/react/properties.py:56–112

class ObservableList(UserList):
    def __init__(self, initlist: Optional[Iterable[_T]] = None) -> None:
        super().__init__()
        self._observers = []

        if initlist:
            self.extend(initlist)

    def subscribe(self, observer):
        self._observers.append(observer)

    def unsubscribe(self, observer):
        self._observers.remove(observer)

    def append(self, item: _T) -> None:
        super().append(item)

        for observer in self._observers:
            observer.on_add(item, len(self.data) - 1)

    def insert(self, i: int, item: _T) -> None:
        super().insert(i, item)

        for observer in self._observers:
            observer.on_add(item, i)

    def pop(self, i: int = ...) -> _T:
        item = super().pop(i)

        for observer in self._observers:
            observer.on_remove(item)

        return item

    def remove(self, item: _T) -> None:
        super().remove(item)

        for observer in self._observers:
            observer.on_remove(item)

    def clear(self) -> None:
        copy = list(self.data)

        super().clear()

        for item in copy:
            for observer in self._observers:
                observer.on_remove(item)

    def extend(self, other: Iterable[_T]) -> None:
        first_index = len(self.data)

        super().extend(other)

        for i, item in enumerate(other):
            for observer in self._observers:
                observer.on_add(item, first_index + i)