basic subscriptions system

1 files changed, 252 insertions, 0 deletions

diff --git a/python/attr/__init__.pyi b/python/attr/__init__.pyi
new file mode 100644
index 0000000..492fb85
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+++ b/python/attr/__init__.pyi
@@ -0,0 +1,252 @@
+from typing import (
+    Any,
+    Callable,
+    Dict,
+    Generic,
+    List,
+    Optional,
+    Sequence,
+    Mapping,
+    Tuple,
+    Type,
+    TypeVar,
+    Union,
+    overload,
+)
+
+# `import X as X` is required to make these public
+from . import exceptions as exceptions
+from . import filters as filters
+from . import converters as converters
+from . import validators as validators
+
+_T = TypeVar("_T")
+_C = TypeVar("_C", bound=type)
+
+_ValidatorType = Callable[[Any, Attribute, _T], Any]
+_ConverterType = Callable[[Any], _T]
+_FilterType = Callable[[Attribute, Any], bool]
+# FIXME: in reality, if multiple validators are passed they must be in a list or tuple,
+# but those are invariant and so would prevent subtypes of _ValidatorType from working
+# when passed in a list or tuple.
+_ValidatorArgType = Union[_ValidatorType[_T], Sequence[_ValidatorType[_T]]]
+
+# _make --
+
+NOTHING: object
+
+# NOTE: Factory lies about its return type to make this possible: `x: List[int] = Factory(list)`
+# Work around mypy issue #4554 in the common case by using an overload.
+@overload
+def Factory(factory: Callable[[], _T]) -> _T: ...
+@overload
+def Factory(
+    factory: Union[Callable[[Any], _T], Callable[[], _T]],
+    takes_self: bool = ...,
+) -> _T: ...
+
+class Attribute(Generic[_T]):
+    name: str
+    default: Optional[_T]
+    validator: Optional[_ValidatorType[_T]]
+    repr: bool
+    cmp: bool
+    hash: Optional[bool]
+    init: bool
+    converter: Optional[_ConverterType[_T]]
+    metadata: Dict[Any, Any]
+    type: Optional[Type[_T]]
+    kw_only: bool
+    def __lt__(self, x: Attribute) -> bool: ...
+    def __le__(self, x: Attribute) -> bool: ...
+    def __gt__(self, x: Attribute) -> bool: ...
+    def __ge__(self, x: Attribute) -> bool: ...
+
+# NOTE: We had several choices for the annotation to use for type arg:
+# 1) Type[_T]
+#   - Pros: Handles simple cases correctly
+#   - Cons: Might produce less informative errors in the case of conflicting TypeVars
+#   e.g. `attr.ib(default='bad', type=int)`
+# 2) Callable[..., _T]
+#   - Pros: Better error messages than #1 for conflicting TypeVars
+#   - Cons: Terrible error messages for validator checks.
+#   e.g. attr.ib(type=int, validator=validate_str)
+#        -> error: Cannot infer function type argument
+# 3) type (and do all of the work in the mypy plugin)
+#   - Pros: Simple here, and we could customize the plugin with our own errors.
+#   - Cons: Would need to write mypy plugin code to handle all the cases.
+# We chose option #1.
+
+# `attr` lies about its return type to make the following possible:
+#     attr()    -> Any
+#     attr(8)   -> int
+#     attr(validator=<some callable>)  -> Whatever the callable expects.
+# This makes this type of assignments possible:
+#     x: int = attr(8)
+#
+# This form catches explicit None or no default but with no other arguments returns Any.
+@overload
+def attrib(
+    default: None = ...,
+    validator: None = ...,
+    repr: bool = ...,
+    cmp: bool = ...,
+    hash: Optional[bool] = ...,
+    init: bool = ...,
+    convert: None = ...,
+    metadata: Optional[Mapping[Any, Any]] = ...,
+    type: None = ...,
+    converter: None = ...,
+    factory: None = ...,
+    kw_only: bool = ...,
+) -> Any: ...
+
+# This form catches an explicit None or no default and infers the type from the other arguments.
+@overload
+def attrib(
+    default: None = ...,
+    validator: Optional[_ValidatorArgType[_T]] = ...,
+    repr: bool = ...,
+    cmp: bool = ...,
+    hash: Optional[bool] = ...,
+    init: bool = ...,
+    convert: Optional[_ConverterType[_T]] = ...,
+    metadata: Optional[Mapping[Any, Any]] = ...,
+    type: Optional[Type[_T]] = ...,
+    converter: Optional[_ConverterType[_T]] = ...,
+    factory: Optional[Callable[[], _T]] = ...,
+    kw_only: bool = ...,
+) -> _T: ...
+
+# This form catches an explicit default argument.
+@overload
+def attrib(
+    default: _T,
+    validator: Optional[_ValidatorArgType[_T]] = ...,
+    repr: bool = ...,
+    cmp: bool = ...,
+    hash: Optional[bool] = ...,
+    init: bool = ...,
+    convert: Optional[_ConverterType[_T]] = ...,
+    metadata: Optional[Mapping[Any, Any]] = ...,
+    type: Optional[Type[_T]] = ...,
+    converter: Optional[_ConverterType[_T]] = ...,
+    factory: Optional[Callable[[], _T]] = ...,
+    kw_only: bool = ...,
+) -> _T: ...
+
+# This form covers type=non-Type: e.g. forward references (str), Any
+@overload
+def attrib(
+    default: Optional[_T] = ...,
+    validator: Optional[_ValidatorArgType[_T]] = ...,
+    repr: bool = ...,
+    cmp: bool = ...,
+    hash: Optional[bool] = ...,
+    init: bool = ...,
+    convert: Optional[_ConverterType[_T]] = ...,
+    metadata: Optional[Mapping[Any, Any]] = ...,
+    type: object = ...,
+    converter: Optional[_ConverterType[_T]] = ...,
+    factory: Optional[Callable[[], _T]] = ...,
+    kw_only: bool = ...,
+) -> Any: ...
+@overload
+def attrs(
+    maybe_cls: _C,
+    these: Optional[Dict[str, Any]] = ...,
+    repr_ns: Optional[str] = ...,
+    repr: bool = ...,
+    cmp: bool = ...,
+    hash: Optional[bool] = ...,
+    init: bool = ...,
+    slots: bool = ...,
+    frozen: bool = ...,
+    weakref_slot: bool = ...,
+    str: bool = ...,
+    auto_attribs: bool = ...,
+    kw_only: bool = ...,
+    cache_hash: bool = ...,
+) -> _C: ...
+@overload
+def attrs(
+    maybe_cls: None = ...,
+    these: Optional[Dict[str, Any]] = ...,
+    repr_ns: Optional[str] = ...,
+    repr: bool = ...,
+    cmp: bool = ...,
+    hash: Optional[bool] = ...,
+    init: bool = ...,
+    slots: bool = ...,
+    frozen: bool = ...,
+    weakref_slot: bool = ...,
+    str: bool = ...,
+    auto_attribs: bool = ...,
+    kw_only: bool = ...,
+    cache_hash: bool = ...,
+) -> Callable[[_C], _C]: ...
+
+# TODO: add support for returning NamedTuple from the mypy plugin
+class _Fields(Tuple[Attribute, ...]):
+    def __getattr__(self, name: str) -> Attribute: ...
+
+def fields(cls: type) -> _Fields: ...
+def fields_dict(cls: type) -> Dict[str, Attribute]: ...
+def validate(inst: Any) -> None: ...
+
+# TODO: add support for returning a proper attrs class from the mypy plugin
+# we use Any instead of _CountingAttr so that e.g. `make_class('Foo', [attr.ib()])` is valid
+def make_class(
+    name: str,
+    attrs: Union[List[str], Tuple[str, ...], Dict[str, Any]],
+    bases: Tuple[type, ...] = ...,
+    repr_ns: Optional[str] = ...,
+    repr: bool = ...,
+    cmp: bool = ...,
+    hash: Optional[bool] = ...,
+    init: bool = ...,
+    slots: bool = ...,
+    frozen: bool = ...,
+    weakref_slot: bool = ...,
+    str: bool = ...,
+    auto_attribs: bool = ...,
+    kw_only: bool = ...,
+    cache_hash: bool = ...,
+) -> type: ...
+
+# _funcs --
+
+# TODO: add support for returning TypedDict from the mypy plugin
+# FIXME: asdict/astuple do not honor their factory args.  waiting on one of these:
+# https://github.com/python/mypy/issues/4236
+# https://github.com/python/typing/issues/253
+def asdict(
+    inst: Any,
+    recurse: bool = ...,
+    filter: Optional[_FilterType] = ...,
+    dict_factory: Type[Mapping[Any, Any]] = ...,
+    retain_collection_types: bool = ...,
+) -> Dict[str, Any]: ...
+
+# TODO: add support for returning NamedTuple from the mypy plugin
+def astuple(
+    inst: Any,
+    recurse: bool = ...,
+    filter: Optional[_FilterType] = ...,
+    tuple_factory: Type[Sequence] = ...,
+    retain_collection_types: bool = ...,
+) -> Tuple[Any, ...]: ...
+def has(cls: type) -> bool: ...
+def assoc(inst: _T, **changes: Any) -> _T: ...
+def evolve(inst: _T, **changes: Any) -> _T: ...
+
+# _config --
+
+def set_run_validators(run: bool) -> None: ...
+def get_run_validators() -> bool: ...
+
+# aliases --
+
+s = attributes = attrs
+ib = attr = attrib
+dataclass = attrs  # Technically, partial(attrs, auto_attribs=True) ;)