JezK
Edit File: runtime.py
"""The runtime functions and state used by compiled templates.""" import functools import sys import typing as t from collections import abc from itertools import chain from markupsafe import escape # noqa: F401 from markupsafe import Markup from markupsafe import soft_str from .async_utils import auto_aiter from .async_utils import auto_await # noqa: F401 from .exceptions import TemplateNotFound # noqa: F401 from .exceptions import TemplateRuntimeError # noqa: F401 from .exceptions import UndefinedError from .nodes import EvalContext from .utils import _PassArg from .utils import concat from .utils import internalcode from .utils import missing from .utils import Namespace # noqa: F401 from .utils import object_type_repr from .utils import pass_eval_context V = t.TypeVar("V") F = t.TypeVar("F", bound=t.Callable[..., t.Any]) if t.TYPE_CHECKING: import logging import typing_extensions as te from .environment import Environment class LoopRenderFunc(te.Protocol): def __call__( self, reciter: t.Iterable[V], loop_render_func: "LoopRenderFunc", depth: int = 0, ) -> str: ... # these variables are exported to the template runtime exported = [ "LoopContext", "TemplateReference", "Macro", "Markup", "TemplateRuntimeError", "missing", "escape", "markup_join", "str_join", "identity", "TemplateNotFound", "Namespace", "Undefined", "internalcode", ] async_exported = [ "AsyncLoopContext", "auto_aiter", "auto_await", ] def identity(x: V) -> V: """Returns its argument. Useful for certain things in the environment. """ return x def markup_join(seq: t.Iterable[t.Any]) -> str: """Concatenation that escapes if necessary and converts to string.""" buf = [] iterator = map(soft_str, seq) for arg in iterator: buf.append(arg) if hasattr(arg, "__html__"): return Markup("").join(chain(buf, iterator)) return concat(buf) def str_join(seq: t.Iterable[t.Any]) -> str: """Simple args to string conversion and concatenation.""" return concat(map(str, seq)) def new_context( environment: "Environment", template_name: t.Optional[str], blocks: t.Dict[str, t.Callable[["Context"], t.Iterator[str]]], vars: t.Optional[t.Dict[str, t.Any]] = None, shared: bool = False, globals: t.Optional[t.MutableMapping[str, t.Any]] = None, locals: t.Optional[t.Mapping[str, t.Any]] = None, ) -> "Context": """Internal helper for context creation.""" if vars is None: vars = {} if shared: parent = vars else: parent = dict(globals or (), **vars) if locals: # if the parent is shared a copy should be created because # we don't want to modify the dict passed if shared: parent = dict(parent) for key, value in locals.items(): if value is not missing: parent[key] = value return environment.context_class( environment, parent, template_name, blocks, globals=globals ) class TemplateReference: """The `self` in templates.""" def __init__(self, context: "Context") -> None: self.__context = context def __getitem__(self, name: str) -> t.Any: blocks = self.__context.blocks[name] return BlockReference(name, self.__context, blocks, 0) def __repr__(self) -> str: return f"<{type(self).__name__} {self.__context.name!r}>" def _dict_method_all(dict_method: F) -> F: @functools.wraps(dict_method) def f_all(self: "Context") -> t.Any: return dict_method(self.get_all()) return t.cast(F, f_all) @abc.Mapping.register class Context: """The template context holds the variables of a template. It stores the values passed to the template and also the names the template exports. Creating instances is neither supported nor useful as it's created automatically at various stages of the template evaluation and should not be created by hand. The context is immutable. Modifications on :attr:`parent` **must not** happen and modifications on :attr:`vars` are allowed from generated template code only. Template filters and global functions marked as :func:`pass_context` get the active context passed as first argument and are allowed to access the context read-only. The template context supports read only dict operations (`get`, `keys`, `values`, `items`, `iterkeys`, `itervalues`, `iteritems`, `__getitem__`, `__contains__`). Additionally there is a :meth:`resolve` method that doesn't fail with a `KeyError` but returns an :class:`Undefined` object for missing variables. """ def __init__( self, environment: "Environment", parent: t.Dict[str, t.Any], name: t.Optional[str], blocks: t.Dict[str, t.Callable[["Context"], t.Iterator[str]]], globals: t.Optional[t.MutableMapping[str, t.Any]] = None, ): self.parent = parent self.vars: t.Dict[str, t.Any] = {} self.environment: "Environment" = environment self.eval_ctx = EvalContext(self.environment, name) self.exported_vars: t.Set[str] = set() self.name = name self.globals_keys = set() if globals is None else set(globals) # create the initial mapping of blocks. Whenever template inheritance # takes place the runtime will update this mapping with the new blocks # from the template. self.blocks = {k: [v] for k, v in blocks.items()} def super( self, name: str, current: t.Callable[["Context"], t.Iterator[str]] ) -> t.Union["BlockReference", "Undefined"]: """Render a parent block.""" try: blocks = self.blocks[name] index = blocks.index(current) + 1 blocks[index] except LookupError: return self.environment.undefined( f"there is no parent block called {name!r}.", name="super" ) return BlockReference(name, self, blocks, index) def get(self, key: str, default: t.Any = None) -> t.Any: """Look up a variable by name, or return a default if the key is not found. :param key: The variable name to look up. :param default: The value to return if the key is not found. """ try: return self[key] except KeyError: return default def resolve(self, key: str) -> t.Union[t.Any, "Undefined"]: """Look up a variable by name, or return an :class:`Undefined` object if the key is not found. If you need to add custom behavior, override :meth:`resolve_or_missing`, not this method. The various lookup functions use that method, not this one. :param key: The variable name to look up. """ rv = self.resolve_or_missing(key) if rv is missing: return self.environment.undefined(name=key) return rv def resolve_or_missing(self, key: str) -> t.Any: """Look up a variable by name, or return a ``missing`` sentinel if the key is not found. Override this method to add custom lookup behavior. :meth:`resolve`, :meth:`get`, and :meth:`__getitem__` use this method. Don't call this method directly. :param key: The variable name to look up. """ if key in self.vars: return self.vars[key] if key in self.parent: return self.parent[key] return missing def get_exported(self) -> t.Dict[str, t.Any]: """Get a new dict with the exported variables.""" return {k: self.vars[k] for k in self.exported_vars} def get_all(self) -> t.Dict[str, t.Any]: """Return the complete context as dict including the exported variables. For optimizations reasons this might not return an actual copy so be careful with using it. """ if not self.vars: return self.parent if not self.parent: return self.vars return dict(self.parent, **self.vars) @internalcode def call( __self, __obj: t.Callable, *args: t.Any, **kwargs: t.Any # noqa: B902 ) -> t.Union[t.Any, "Undefined"]: """Call the callable with the arguments and keyword arguments provided but inject the active context or environment as first argument if the callable has :func:`pass_context` or :func:`pass_environment`. """ if __debug__: __traceback_hide__ = True # noqa # Allow callable classes to take a context if ( hasattr(__obj, "__call__") # noqa: B004 and _PassArg.from_obj(__obj.__call__) is not None # type: ignore ): __obj = __obj.__call__ # type: ignore pass_arg = _PassArg.from_obj(__obj) if pass_arg is _PassArg.context: # the active context should have access to variables set in # loops and blocks without mutating the context itself if kwargs.get("_loop_vars"): __self = __self.derived(kwargs["_loop_vars"]) if kwargs.get("_block_vars"): __self = __self.derived(kwargs["_block_vars"]) args = (__self,) + args elif pass_arg is _PassArg.eval_context: args = (__self.eval_ctx,) + args elif pass_arg is _PassArg.environment: args = (__self.environment,) + args kwargs.pop("_block_vars", None) kwargs.pop("_loop_vars", None) try: return __obj(*args, **kwargs) except StopIteration: return __self.environment.undefined( "value was undefined because a callable raised a" " StopIteration exception" ) def derived(self, locals: t.Optional[t.Dict[str, t.Any]] = None) -> "Context": """Internal helper function to create a derived context. This is used in situations where the system needs a new context in the same template that is independent. """ context = new_context( self.environment, self.name, {}, self.get_all(), True, None, locals ) context.eval_ctx = self.eval_ctx context.blocks.update((k, list(v)) for k, v in self.blocks.items()) return context keys = _dict_method_all(dict.keys) values = _dict_method_all(dict.values) items = _dict_method_all(dict.items) def __contains__(self, name: str) -> bool: return name in self.vars or name in self.parent def __getitem__(self, key: str) -> t.Any: """Look up a variable by name with ``[]`` syntax, or raise a ``KeyError`` if the key is not found. """ item = self.resolve_or_missing(key) if item is missing: raise KeyError(key) return item def __repr__(self) -> str: return f"<{type(self).__name__} {self.get_all()!r} of {self.name!r}>" class BlockReference: """One block on a template reference.""" def __init__( self, name: str, context: "Context", stack: t.List[t.Callable[["Context"], t.Iterator[str]]], depth: int, ) -> None: self.name = name self._context = context self._stack = stack self._depth = depth @property def super(self) -> t.Union["BlockReference", "Undefined"]: """Super the block.""" if self._depth + 1 >= len(self._stack): return self._context.environment.undefined( f"there is no parent block called {self.name!r}.", name="super" ) return BlockReference(self.name, self._context, self._stack, self._depth + 1) @internalcode async def _async_call(self) -> str: rv = concat( [x async for x in self._stack[self._depth](self._context)] # type: ignore ) if self._context.eval_ctx.autoescape: return Markup(rv) return rv @internalcode def __call__(self) -> str: if self._context.environment.is_async: return self._async_call() # type: ignore rv = concat(self._stack[self._depth](self._context)) if self._context.eval_ctx.autoescape: return Markup(rv) return rv class LoopContext: """A wrapper iterable for dynamic ``for`` loops, with information about the loop and iteration. """ #: Current iteration of the loop, starting at 0. index0 = -1 _length: t.Optional[int] = None _after: t.Any = missing _current: t.Any = missing _before: t.Any = missing _last_changed_value: t.Any = missing def __init__( self, iterable: t.Iterable[V], undefined: t.Type["Undefined"], recurse: t.Optional["LoopRenderFunc"] = None, depth0: int = 0, ) -> None: """ :param iterable: Iterable to wrap. :param undefined: :class:`Undefined` class to use for next and previous items. :param recurse: The function to render the loop body when the loop is marked recursive. :param depth0: Incremented when looping recursively. """ self._iterable = iterable self._iterator = self._to_iterator(iterable) self._undefined = undefined self._recurse = recurse #: How many levels deep a recursive loop currently is, starting at 0. self.depth0 = depth0 @staticmethod def _to_iterator(iterable: t.Iterable[V]) -> t.Iterator[V]: return iter(iterable) @property def length(self) -> int: """Length of the iterable. If the iterable is a generator or otherwise does not have a size, it is eagerly evaluated to get a size. """ if self._length is not None: return self._length try: self._length = len(self._iterable) # type: ignore except TypeError: iterable = list(self._iterator) self._iterator = self._to_iterator(iterable) self._length = len(iterable) + self.index + (self._after is not missing) return self._length def __len__(self) -> int: return self.length @property def depth(self) -> int: """How many levels deep a recursive loop currently is, starting at 1.""" return self.depth0 + 1 @property def index(self) -> int: """Current iteration of the loop, starting at 1.""" return self.index0 + 1 @property def revindex0(self) -> int: """Number of iterations from the end of the loop, ending at 0. Requires calculating :attr:`length`. """ return self.length - self.index @property def revindex(self) -> int: """Number of iterations from the end of the loop, ending at 1. Requires calculating :attr:`length`. """ return self.length - self.index0 @property def first(self) -> bool: """Whether this is the first iteration of the loop.""" return self.index0 == 0 def _peek_next(self) -> t.Any: """Return the next element in the iterable, or :data:`missing` if the iterable is exhausted. Only peeks one item ahead, caching the result in :attr:`_last` for use in subsequent checks. The cache is reset when :meth:`__next__` is called. """ if self._after is not missing: return self._after self._after = next(self._iterator, missing) return self._after @property def last(self) -> bool: """Whether this is the last iteration of the loop. Causes the iterable to advance early. See :func:`itertools.groupby` for issues this can cause. The :func:`groupby` filter avoids that issue. """ return self._peek_next() is missing @property def previtem(self) -> t.Union[t.Any, "Undefined"]: """The item in the previous iteration. Undefined during the first iteration. """ if self.first: return self._undefined("there is no previous item") return self._before @property def nextitem(self) -> t.Union[t.Any, "Undefined"]: """The item in the next iteration. Undefined during the last iteration. Causes the iterable to advance early. See :func:`itertools.groupby` for issues this can cause. The :func:`jinja-filters.groupby` filter avoids that issue. """ rv = self._peek_next() if rv is missing: return self._undefined("there is no next item") return rv def cycle(self, *args: V) -> V: """Return a value from the given args, cycling through based on the current :attr:`index0`. :param args: One or more values to cycle through. """ if not args: raise TypeError("no items for cycling given") return args[self.index0 % len(args)] def changed(self, *value: t.Any) -> bool: """Return ``True`` if previously called with a different value (including when called for the first time). :param value: One or more values to compare to the last call. """ if self._last_changed_value != value: self._last_changed_value = value return True return False def __iter__(self) -> "LoopContext": return self def __next__(self) -> t.Tuple[t.Any, "LoopContext"]: if self._after is not missing: rv = self._after self._after = missing else: rv = next(self._iterator) self.index0 += 1 self._before = self._current self._current = rv return rv, self @internalcode def __call__(self, iterable: t.Iterable[V]) -> str: """When iterating over nested data, render the body of the loop recursively with the given inner iterable data. The loop must have the ``recursive`` marker for this to work. """ if self._recurse is None: raise TypeError( "The loop must have the 'recursive' marker to be called recursively." ) return self._recurse(iterable, self._recurse, depth=self.depth) def __repr__(self) -> str: return f"<{type(self).__name__} {self.index}/{self.length}>" class AsyncLoopContext(LoopContext): _iterator: t.AsyncIterator[t.Any] # type: ignore @staticmethod def _to_iterator( # type: ignore iterable: t.Union[t.Iterable[V], t.AsyncIterable[V]] ) -> t.AsyncIterator[V]: return auto_aiter(iterable) @property async def length(self) -> int: # type: ignore if self._length is not None: return self._length try: self._length = len(self._iterable) # type: ignore except TypeError: iterable = [x async for x in self._iterator] self._iterator = self._to_iterator(iterable) self._length = len(iterable) + self.index + (self._after is not missing) return self._length @property async def revindex0(self) -> int: # type: ignore return await self.length - self.index @property async def revindex(self) -> int: # type: ignore return await self.length - self.index0 async def _peek_next(self) -> t.Any: if self._after is not missing: return self._after try: self._after = await self._iterator.__anext__() except StopAsyncIteration: self._after = missing return self._after @property async def last(self) -> bool: # type: ignore return await self._peek_next() is missing @property async def nextitem(self) -> t.Union[t.Any, "Undefined"]: rv = await self._peek_next() if rv is missing: return self._undefined("there is no next item") return rv def __aiter__(self) -> "AsyncLoopContext": return self async def __anext__(self) -> t.Tuple[t.Any, "AsyncLoopContext"]: if self._after is not missing: rv = self._after self._after = missing else: rv = await self._iterator.__anext__() self.index0 += 1 self._before = self._current self._current = rv return rv, self class Macro: """Wraps a macro function.""" def __init__( self, environment: "Environment", func: t.Callable[..., str], name: str, arguments: t.List[str], catch_kwargs: bool, catch_varargs: bool, caller: bool, default_autoescape: t.Optional[bool] = None, ): self._environment = environment self._func = func self._argument_count = len(arguments) self.name = name self.arguments = arguments self.catch_kwargs = catch_kwargs self.catch_varargs = catch_varargs self.caller = caller self.explicit_caller = "caller" in arguments if default_autoescape is None: if callable(environment.autoescape): default_autoescape = environment.autoescape(None) else: default_autoescape = environment.autoescape self._default_autoescape = default_autoescape @internalcode @pass_eval_context def __call__(self, *args: t.Any, **kwargs: t.Any) -> str: # This requires a bit of explanation, In the past we used to # decide largely based on compile-time information if a macro is # safe or unsafe. While there was a volatile mode it was largely # unused for deciding on escaping. This turns out to be # problematic for macros because whether a macro is safe depends not # on the escape mode when it was defined, but rather when it was used. # # Because however we export macros from the module system and # there are historic callers that do not pass an eval context (and # will continue to not pass one), we need to perform an instance # check here. # # This is considered safe because an eval context is not a valid # argument to callables otherwise anyway. Worst case here is # that if no eval context is passed we fall back to the compile # time autoescape flag. if args and isinstance(args[0], EvalContext): autoescape = args[0].autoescape args = args[1:] else: autoescape = self._default_autoescape # try to consume the positional arguments arguments = list(args[: self._argument_count]) off = len(arguments) # For information why this is necessary refer to the handling # of caller in the `macro_body` handler in the compiler. found_caller = False # if the number of arguments consumed is not the number of # arguments expected we start filling in keyword arguments # and defaults. if off != self._argument_count: for name in self.arguments[len(arguments) :]: try: value = kwargs.pop(name) except KeyError: value = missing if name == "caller": found_caller = True arguments.append(value) else: found_caller = self.explicit_caller # it's important that the order of these arguments does not change # if not also changed in the compiler's `function_scoping` method. # the order is caller, keyword arguments, positional arguments! if self.caller and not found_caller: caller = kwargs.pop("caller", None) if caller is None: caller = self._environment.undefined("No caller defined", name="caller") arguments.append(caller) if self.catch_kwargs: arguments.append(kwargs) elif kwargs: if "caller" in kwargs: raise TypeError( f"macro {self.name!r} was invoked with two values for the special" " caller argument. This is most likely a bug." ) raise TypeError( f"macro {self.name!r} takes no keyword argument {next(iter(kwargs))!r}" ) if self.catch_varargs: arguments.append(args[self._argument_count :]) elif len(args) > self._argument_count: raise TypeError( f"macro {self.name!r} takes not more than" f" {len(self.arguments)} argument(s)" ) return self._invoke(arguments, autoescape) async def _async_invoke(self, arguments: t.List[t.Any], autoescape: bool) -> str: rv = await self._func(*arguments) # type: ignore if autoescape: return Markup(rv) return rv # type: ignore def _invoke(self, arguments: t.List[t.Any], autoescape: bool) -> str: if self._environment.is_async: return self._async_invoke(arguments, autoescape) # type: ignore rv = self._func(*arguments) if autoescape: rv = Markup(rv) return rv def __repr__(self) -> str: name = "anonymous" if self.name is None else repr(self.name) return f"<{type(self).__name__} {name}>" class Undefined: """The default undefined type. This undefined type can be printed and iterated over, but every other access will raise an :exc:`UndefinedError`: >>> foo = Undefined(name='foo') >>> str(foo) '' >>> not foo True >>> foo + 42 Traceback (most recent call last): ... jinja2.exceptions.UndefinedError: 'foo' is undefined """ __slots__ = ( "_undefined_hint", "_undefined_obj", "_undefined_name", "_undefined_exception", ) def __init__( self, hint: t.Optional[str] = None, obj: t.Any = missing, name: t.Optional[str] = None, exc: t.Type[TemplateRuntimeError] = UndefinedError, ) -> None: self._undefined_hint = hint self._undefined_obj = obj self._undefined_name = name self._undefined_exception = exc @property def _undefined_message(self) -> str: """Build a message about the undefined value based on how it was accessed. """ if self._undefined_hint: return self._undefined_hint if self._undefined_obj is missing: return f"{self._undefined_name!r} is undefined" if not isinstance(self._undefined_name, str): return ( f"{object_type_repr(self._undefined_obj)} has no" f" element {self._undefined_name!r}" ) return ( f"{object_type_repr(self._undefined_obj)!r} has no" f" attribute {self._undefined_name!r}" ) @internalcode def _fail_with_undefined_error( self, *args: t.Any, **kwargs: t.Any ) -> "te.NoReturn": """Raise an :exc:`UndefinedError` when operations are performed on the undefined value. """ raise self._undefined_exception(self._undefined_message) @internalcode def __getattr__(self, name: str) -> t.Any: if name[:2] == "__": raise AttributeError(name) return self._fail_with_undefined_error() __add__ = __radd__ = __sub__ = __rsub__ = _fail_with_undefined_error __mul__ = __rmul__ = __div__ = __rdiv__ = _fail_with_undefined_error __truediv__ = __rtruediv__ = _fail_with_undefined_error __floordiv__ = __rfloordiv__ = _fail_with_undefined_error __mod__ = __rmod__ = _fail_with_undefined_error __pos__ = __neg__ = _fail_with_undefined_error __call__ = __getitem__ = _fail_with_undefined_error __lt__ = __le__ = __gt__ = __ge__ = _fail_with_undefined_error __int__ = __float__ = __complex__ = _fail_with_undefined_error __pow__ = __rpow__ = _fail_with_undefined_error def __eq__(self, other: t.Any) -> bool: return type(self) is type(other) def __ne__(self, other: t.Any) -> bool: return not self.__eq__(other) def __hash__(self) -> int: return id(type(self)) def __str__(self) -> str: return "" def __len__(self) -> int: return 0 def __iter__(self) -> t.Iterator[t.Any]: yield from () async def __aiter__(self) -> t.AsyncIterator[t.Any]: for _ in (): yield def __bool__(self) -> bool: return False def __repr__(self) -> str: return "Undefined" def make_logging_undefined( logger: t.Optional["logging.Logger"] = None, base: t.Type[Undefined] = Undefined ) -> t.Type[Undefined]: """Given a logger object this returns a new undefined class that will log certain failures. It will log iterations and printing. If no logger is given a default logger is created. Example:: logger = logging.getLogger(__name__) LoggingUndefined = make_logging_undefined( logger=logger, base=Undefined ) .. versionadded:: 2.8 :param logger: the logger to use. If not provided, a default logger is created. :param base: the base class to add logging functionality to. This defaults to :class:`Undefined`. """ if logger is None: import logging logger = logging.getLogger(__name__) logger.addHandler(logging.StreamHandler(sys.stderr)) def _log_message(undef: Undefined) -> None: logger.warning( # type: ignore "Template variable warning: %s", undef._undefined_message ) class LoggingUndefined(base): # type: ignore __slots__ = () def _fail_with_undefined_error( # type: ignore self, *args: t.Any, **kwargs: t.Any ) -> "te.NoReturn": try: super()._fail_with_undefined_error(*args, **kwargs) except self._undefined_exception as e: logger.error("Template variable error: %s", e) # type: ignore raise e def __str__(self) -> str: _log_message(self) return super().__str__() # type: ignore def __iter__(self) -> t.Iterator[t.Any]: _log_message(self) return super().__iter__() # type: ignore def __bool__(self) -> bool: _log_message(self) return super().__bool__() # type: ignore return LoggingUndefined class ChainableUndefined(Undefined): """An undefined that is chainable, where both ``__getattr__`` and ``__getitem__`` return itself rather than raising an :exc:`UndefinedError`. >>> foo = ChainableUndefined(name='foo') >>> str(foo.bar['baz']) '' >>> foo.bar['baz'] + 42 Traceback (most recent call last): ... jinja2.exceptions.UndefinedError: 'foo' is undefined .. versionadded:: 2.11.0 """ __slots__ = () def __html__(self) -> str: return str(self) def __getattr__(self, _: str) -> "ChainableUndefined": return self __getitem__ = __getattr__ # type: ignore class DebugUndefined(Undefined): """An undefined that returns the debug info when printed. >>> foo = DebugUndefined(name='foo') >>> str(foo) '{{ foo }}' >>> not foo True >>> foo + 42 Traceback (most recent call last): ... jinja2.exceptions.UndefinedError: 'foo' is undefined """ __slots__ = () def __str__(self) -> str: if self._undefined_hint: message = f"undefined value printed: {self._undefined_hint}" elif self._undefined_obj is missing: message = self._undefined_name # type: ignore else: message = ( f"no such element: {object_type_repr(self._undefined_obj)}" f"[{self._undefined_name!r}]" ) return f"{{{{ {message} }}}}" class StrictUndefined(Undefined): """An undefined that barks on print and iteration as well as boolean tests and all kinds of comparisons. In other words: you can do nothing with it except checking if it's defined using the `defined` test. >>> foo = StrictUndefined(name='foo') >>> str(foo) Traceback (most recent call last): ... jinja2.exceptions.UndefinedError: 'foo' is undefined >>> not foo Traceback (most recent call last): ... jinja2.exceptions.UndefinedError: 'foo' is undefined >>> foo + 42 Traceback (most recent call last): ... jinja2.exceptions.UndefinedError: 'foo' is undefined """ __slots__ = () __iter__ = __str__ = __len__ = Undefined._fail_with_undefined_error __eq__ = __ne__ = __bool__ = __hash__ = Undefined._fail_with_undefined_error __contains__ = Undefined._fail_with_undefined_error # Remove slots attributes, after the metaclass is applied they are # unneeded and contain wrong data for subclasses. del ( Undefined.__slots__, ChainableUndefined.__slots__, DebugUndefined.__slots__, StrictUndefined.__slots__, )