Class HasTraits

traitlets/traitlets.py:1326–2001

class HasTraits(HasDescriptors, metaclass=MetaHasTraits):
    _trait_values: dict[str, t.Any]
    _static_immutable_initial_values: dict[str, t.Any]
    _trait_notifiers: dict[str | Sentinel, t.Any]
    _trait_validators: dict[str | Sentinel, t.Any]
    _cross_validation_lock: bool
    _traits: dict[str, t.Any]
    _all_trait_default_generators: dict[str, t.Any]

    def setup_instance(self, /, *args: t.Any, **kwargs: t.Any) -> None:
        # although we'd prefer to set only the initial values not present
        # in kwargs, we will overwrite them in `__init__`, and simply making
        # a copy of a dict is faster than checking for each key.
        self._trait_values = self._static_immutable_initial_values.copy()
        self._trait_notifiers = {}
        self._trait_validators = {}
        self._cross_validation_lock = False
        super(HasTraits, self).setup_instance(*args, **kwargs)

    def __init__(self, *args: t.Any, **kwargs: t.Any) -> None:
        # Allow trait values to be set using keyword arguments.
        # We need to use setattr for this to trigger validation and
        # notifications.
        super_args = args
        super_kwargs = {}

        if kwargs:
            # this is a simplified (and faster) version of
            # the hold_trait_notifications(self) context manager
            def ignore(change: Bunch) -> None:
                pass

            self.notify_change = ignore  # type:ignore[method-assign]
            self._cross_validation_lock = True
            changes = {}
            for key, value in kwargs.items():
                if self.has_trait(key):
                    setattr(self, key, value)
                    changes[key] = Bunch(
                        name=key,
                        old=None,
                        new=value,
                        owner=self,
                        type="change",
                    )
                else:
                    # passthrough args that don't set traits to super
                    super_kwargs[key] = value
            # notify and cross validate all trait changes that were set in kwargs
            changed = set(kwargs) & set(self._traits)
            for key in changed:
                value = self._traits[key]._cross_validate(self, getattr(self, key))
                self.set_trait(key, value)
                changes[key]["new"] = value
            self._cross_validation_lock = False
            # Restore method retrieval from class
            del self.notify_change
            for key in changed: