8000 Add support for method lookup from Type[]. · python/mypy@52bb2a6 · GitHub
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Guido van Rossum
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Add support for method lookup from Type[].
We only support two special cases (hopefully the most common ones): - Type[<concrete_class>] - Type[<type_variable_with_concrete_class_upper_bound>]
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+92
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lines changed

3 files changed

+92
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‎mypy/checkmember.py

Lines changed: 19 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -4,7 +4,8 @@
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from mypy.types import (
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Type, Instance, AnyType, TupleType, CallableType, FunctionLike, TypeVarDef,
7-
Overloaded, TypeVarType, TypeTranslator, UnionType, PartialType, DeletedType, NoneTyp
7+
Overloaded, TypeVarType, TypeTranslator, UnionType, PartialType,
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DeletedType, NoneTyp, TypeType
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)
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from mypy.nodes import TypeInfo, FuncBase, Var, FuncDef, SymbolNode, Context
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from mypy.nodes import ARG_POS, ARG_STAR, ARG_STAR2, function_type, Decorator, OverloadedFuncDef
@@ -113,6 +114,23 @@ def analyze_member_access(name: str, typ: Type, node: Context, is_lvalue: bool,
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elif isinstance(typ, DeletedType):
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msg.deleted_as_rvalue(typ, node)
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return AnyType()
117+
elif isinstance(typ, TypeType):
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# Similar to FunctionLike + is_type_obj() above.
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item = None
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if isinstance(typ.item, Instance):
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item = typ.item
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elif isinstance(typ.item, TypeVarType):
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if isinstance(typ.item.upper_bound, Instance):
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item = typ.item.upper_bound
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if item:
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result = analyze_class_attribute_access(item, name, node, is_lvalue,
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builtin_type, not_ready_callback, msg)
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if result:
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return result
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fallback = builtin_type('builtins.type')
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return analyze_member_access(name, fallback, node, is_lvalue, is_super,
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builtin_type, not_ready_callback, msg,
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report_type=report_type)
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return msg.has_no_attr(report_type, name, node)
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‎mypy/test/data/check-classes.test

Lines changed: 72 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1527,3 +1527,75 @@ def bar(arg: Type[X]):
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foo(X)
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[builtins fixtures/tuple.py]
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[out]
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[case testTypeUsingTypeCClassMethod]
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from typing import Type
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class User:
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@classmethod
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def foo(cls) -> int: pass
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def bar(self) -> int: pass
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def process(cls: Type[User]):
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reveal_type(cls.foo()) # E: Revealed type is 'builtins.int'
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obj = cls()
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reveal_type(cls.bar(obj)) # E: Revealed type is 'builtins.int'
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cls.mro() # Defined in class type
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cls.error # E: Type[User] has no attribute "error"
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[builtins fixtures/classmethod.py]
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[out]
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main: note: In function "process":
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[case testTypeUsingTypeCClassMethodUnion]
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# Ideally this would work, but not worth the effort; just don't crash
1549+
from typing import Type, Union
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class User:
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@classmethod
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def foo(cls) -> int: pass
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def bar(self) -> int: pass
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class ProUser(User): pass
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class BasicUser(User): pass
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def process(cls: Type[Union[BasicUser, ProUser]]):
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cls.foo() # E: Type[Union[BasicUser, ProUser]] has no attribute "foo"
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obj = cls()
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cls.bar(obj) # E: Type[Union[BasicUser, ProUser]] has no attribute "bar"
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cls.mro() # Defined in class type
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cls.error # E: Type[Union[BasicUser, ProUser]] has no attribute "error"
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[builtins fixtures/classmethod.py]
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[out]
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main: note: In function "process":
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[case testTypeUsingTypeCClassMethodFromTypeVar]
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from typing import Type, TypeVar
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class User:
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@classmethod
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def foo(cls) -> int: pass
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def bar(self) -> int: pass
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U = TypeVar('U', bound=User)
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def process(cls: Type[U]):
1574+
reveal_type(cls.foo()) # E: Revealed type is 'builtins.int'
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obj = cls()
1576+
reveal_type(cls.bar(obj)) # E: Revealed type is 'builtins.int'
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cls.mro() # Defined in class type
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cls.error # E: Type[U] has no attribute "error"
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[builtins fixtures/classmethod.py]
1580+
[out]
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main: note: In function "process":
1582+
1583+
[case testTypeUsingTypeCClassMethodFromTypeVarUnionBound]
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# Ideally this would work, but not worth the effort; just don't crash
1585+
from typing import Type, TypeVar, Union
1586+
class User:
1587+
@classmethod
1588+
def foo(cls) -> int: pass
1589+
def bar(self) -> int: pass
1590+
class ProUser(User): pass
1591+
class BasicUser(User): pass
1592+
U = TypeVar('U', bound=Union[ProUser, BasicUser])
1593+
def process(cls: Type[U]):
1594+
cls.foo() # E: Type[U] has no attribute "foo"
1595+
obj = cls()
1596+
cls.bar(obj) # E: Type[U] has no attribute "bar"
1597+
cls.mro() # Defined in class type
1598+
cls.error # E: Type[U] has no attribute "error"
1599+
[builtins fixtures/classmethod.py]
1600+
[out]
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main: note: In function "process":

‎mypy/test/data/fixtures/classmethod.py

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -5,6 +5,7 @@ def __init__(self) -> None: pass
55

66
class type:
77
def __init__(self, x) -> None: pass
8+
def mro(self) -> typing.Any: pass
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910
class function: pass
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