def analyze_member_access(name: str,
typ: Type,
node: Context,
is_lvalue: bool,
is_super: bool,
is_operator: bool,
builtin_type: Callable[[str], Instance],
not_ready_callback: Callable[[str, Context], None],
msg: MessageBuilder,
*,
original_type: Type,
chk: 'mypy.checker.TypeChecker',
override_info: Optional[TypeInfo] = None) -> Type:
"""Return the type of attribute `name` of typ.
This is a general operation that supports various different variations:
1. lvalue or non-lvalue access (i.e. setter or getter access)
2. supertype access (when using super(); is_super == True and
override_info should refer to the supertype)
original_type is the most precise inferred or declared type of the base object
that we have available. typ is generally a supertype of original_type.
When looking for an attribute of typ, we may perform recursive calls targeting
the fallback type, for example.
original_type is always the type used in the initial call.
"""
# TODO: this and following functions share some logic with subtypes.find_member,
# consider refactoring.
if isinstance(typ, Instance):
if name == '__init__' and not is_super:
# Accessing __init__ in statically typed code would compromise
# type safety unless used via super().
msg.fail(messages.CANNOT_ACCESS_INIT, node)
return AnyType(TypeOfAny.from_error)
# The base object has an instance type.
info = typ.type
if override_info:
info = override_info
if (experiments.find_occurrences
and info.name() == experiments.find_occurrences[0]
and name == experiments.find_occurrences[1]):
msg.note(
"Occurrence of '{}.{}'".format(*experiments.find_occurrences),
node)
# Look up the member. First look up the method dictionary.
method = info.get_method(name)
if method:
if method.is_property:
assert isinstance(method, OverloadedFuncDef)
first_item = cast(Decorator, method.items[0])
return analyze_var(name,
first_item.var,
typ,
info,
node,
is_lvalue,
msg,
original_type,
not_ready_callback,
chk=chk)
if is_lvalue:
msg.cant_assign_to_method(node)
signature = function_type(method,
builtin_type('builtins.function'))
signature = freshen_function_type_vars(signature)
if name == '__new__':
# __new__ is special and behaves like a static method -- don't strip
# the first argument.
pass
else:
signature = bind_self(signature, original_type)
typ = map_instance_to_supertype(typ, method.info)
member_type = expand_type_by_instance(signature, typ)
freeze_type_vars(member_type)
return member_type
else:
# Not a method.
return analyze_member_var_access(name,
typ,
info,
node,
is_lvalue,
is_super,
builtin_type,
not_ready_callback,
msg,
original_type=original_type,
chk=chk)
elif isinstance(typ, AnyType):
# The base object has dynamic type.
return AnyType(TypeOfAny.from_another_any, source_any=typ)
elif isinstance(typ, NoneTyp):
if chk.should_suppress_optional_error([typ]):
return AnyType(TypeOfAny.from_error)
# The only attribute NoneType has are those it inherits from object
return analyze_member_access(name,
builtin_type('builtins.object'),
node,
is_lvalue,
is_super,
is_operator,
builtin_type,
not_ready_callback,
msg,
original_type=original_type,
chk=chk)
elif isinstance(typ, UnionType):
# The base object has dynamic type.
msg.disable_type_names += 1
results = [
analyze_member_access(name,
subtype,
node,
is_lvalue,
is_super,
is_operator,
builtin_type,
not_ready_callback,
msg,
original_type=original_type,
chk=chk) for subtype in typ.relevant_items()
]
msg.disable_type_names -= 1
return UnionType.make_simplified_union(results)
elif isinstance(typ, TupleType):
# Actually look up from the fallback instance type.
return analyze_member_access(name,
typ.fallback,
node,
is_lvalue,
is_super,
is_operator,
builtin_type,
not_ready_callback,
msg,
original_type=original_type,
chk=chk)
elif isinstance(typ, TypedDictType):
# Actually look up from the fallback instance type.
return analyze_member_access(name,
typ.fallback,
node,
is_lvalue,
is_super,
is_operator,
builtin_type,
not_ready_callback,
msg,
original_type=original_type,
chk=chk)
elif isinstance(typ, FunctionLike) and typ.is_type_obj():
# Class attribute.
# TODO super?
ret_type = typ.items()[0].ret_type
if isinstance(ret_type, TupleType):
ret_type = ret_type.fallback
if isinstance(ret_type, Instance):
if not is_operator:
# When Python sees an operator (eg `3 == 4`), it automatically translates that
# into something like `int.__eq__(3, 4)` instead of `(3).__eq__(4)` as an
# optimization.
#
# While it normally it doesn't matter which of the two versions are used, it
# does cause inconsistencies when working with classes. For example, translating
# `int == int` to `int.__eq__(int)` would not work since `int.__eq__` is meant to
# compare two int _instances_. What we really want is `type(int).__eq__`, which
# is meant to compare two types or classes.
#
# This check makes sure that when we encounter an operator, we skip looking up
# the corresponding method in the current instance to avoid this edge case.
# See https://github.com/python/mypy/pull/1787 for more info.
result = analyze_class_attribute_access(
ret_type,
name,
node,
is_lvalue,
builtin_type,
not_ready_callback,
msg,
original_type=original_type)
if result:
return result
# Look up from the 'type' type.
return analyze_member_access(name,
typ.fallback,
node,
is_lvalue,
is_super,
is_operator,
builtin_type,
not_ready_callback,
msg,
original_type=original_type,
chk=chk)
else:
assert False, 'Unexpected type {}'.format(repr(ret_type))
elif isinstance(typ, FunctionLike):
# Look up from the 'function' type.
return analyze_member_access(name,
typ.fallback,
node,
is_lvalue,
is_super,
is_operator,
builtin_type,
not_ready_callback,
msg,
original_type=original_type,
chk=chk)
elif isinstance(typ, TypeVarType):
return analyze_member_access(name,
typ.upper_bound,
node,
is_lvalue,
is_super,
is_operator,
builtin_type,
not_ready_callback,
msg,
original_type=original_type,
chk=chk)
elif isinstance(typ, DeletedType):
msg.deleted_as_rvalue(typ, node)
return AnyType(TypeOfAny.from_error)
elif isinstance(typ, TypeType):
# Similar to FunctionLike + is_type_obj() above.
item = None
fallback = builtin_type('builtins.type')
ignore_messages = msg.copy()
ignore_messages.disable_errors()
if isinstance(typ.item, Instance):
item = typ.item
elif isinstance(typ.item, AnyType):
return analyze_member_access(name,
fallback,
node,
is_lvalue,
is_super,
is_operator,
builtin_type,
not_ready_callback,
ignore_messages,
original_type=original_type,
chk=chk)
elif isinstance(typ.item, TypeVarType):
if isinstance(typ.item.upper_bound, Instance):
item = typ.item.upper_bound
elif isinstance(typ.item, FunctionLike) and typ.item.is_type_obj():
item = typ.item.fallback
elif isinstance(typ.item, TypeType):
# Access member on metaclass object via Type[Type[C]]
if isinstance(typ.item.item, Instance):
item = typ.item.item.type.metaclass_type
if item and not is_operator:
# See comment above for why operators are skipped
result = analyze_class_attribute_access(
item,
name,
node,
is_lvalue,
builtin_type,
not_ready_callback,
msg,
original_type=original_type)
if result:
if not (isinstance(result, AnyType)
and item.type.fallback_to_any):
return result
else:
# We don't want errors on metaclass lookup for classes with Any fallback
msg = ignore_messages
if item is not None:
fallback = item.type.metaclass_type or fallback
return analyze_member_access(name,
fallback,
node,
is_lvalue,
is_super,
is_operator,
builtin_type,
not_ready_callback,
msg,
original_type=original_type,
chk=chk)
if chk.should_suppress_optional_error([typ]):
return AnyType(TypeOfAny.from_error)
return msg.has_no_attr(original_type, typ, name, node)
def analyze_member_access(name: str,
typ: Type,
node: Context,
is_lvalue: bool,
is_super: bool,
is_operator: bool,
builtin_type: Callable[[str], Instance],
not_ready_callback: Callable[[str, Context], None],
msg: MessageBuilder, *,
original_type: Type,
chk: 'mypy.checker.TypeChecker',
override_info: Optional[TypeInfo] = None) -> Type:
"""Return the type of attribute `name` of typ.
This is a general operation that supports various different variations:
1. lvalue or non-lvalue access (i.e. setter or getter access)
2. supertype access (when using super(); is_super == True and
override_info should refer to the supertype)
original_type is the most precise inferred or declared type of the base object
that we have available. typ is generally a supertype of original_type.
When looking for an attribute of typ, we may perform recursive calls targeting
the fallback type, for example.
original_type is always the type used in the initial call.
"""
# TODO: this and following functions share some logic with subtypes.find_member,
# consider refactoring.
if isinstance(typ, Instance):
if name == '__init__' and not is_super:
# Accessing __init__ in statically typed code would compromise
# type safety unless used via super().
msg.fail(messages.CANNOT_ACCESS_INIT, node)
return AnyType(TypeOfAny.from_error)
# The base object has an instance type.
info = typ.type
if override_info:
info = override_info
if (experiments.find_occurrences and
info.name() == experiments.find_occurrences[0] and
name == experiments.find_occurrences[1]):
msg.note("Occurrence of '{}.{}'".format(*experiments.find_occurrences), node)
# Look up the member. First look up the method dictionary.
method = info.get_method(name)
if method:
if method.is_property:
assert isinstance(method, OverloadedFuncDef)
first_item = cast(Decorator, method.items[0])
return analyze_var(name, first_item.var, typ, info, node, is_lvalue, msg,
original_type, not_ready_callback, chk=chk)
if is_lvalue:
msg.cant_assign_to_method(node)
signature = function_type(method, builtin_type('builtins.function'))
signature = freshen_function_type_vars(signature)
if name == '__new__':
# __new__ is special and behaves like a static method -- don't strip
# the first argument.
pass
else:
signature = bind_self(signature, original_type)
typ = map_instance_to_supertype(typ, method.info)
member_type = expand_type_by_instance(signature, typ)
freeze_type_vars(member_type)
return member_type
else:
# Not a method.
return analyze_member_var_access(name, typ, info, node,
is_lvalue, is_super, builtin_type,
not_ready_callback, msg,
original_type=original_type, chk=chk)
elif isinstance(typ, AnyType):
# The base object has dynamic type.
return AnyType(TypeOfAny.from_another_any, source_any=typ)
elif isinstance(typ, NoneTyp):
if chk.should_suppress_optional_error([typ]):
return AnyType(TypeOfAny.from_error)
# The only attribute NoneType has are those it inherits from object
return analyze_member_access(name, builtin_type('builtins.object'), node, is_lvalue,
is_super, is_operator, builtin_type, not_ready_callback, msg,
original_type=original_type, chk=chk)
elif isinstance(typ, UnionType):
# The base object has dynamic type.
msg.disable_type_names += 1
results = [analyze_member_access(name, subtype, node, is_lvalue, is_super,
is_operator, builtin_type, not_ready_callback, msg,
original_type=original_type, chk=chk)
for subtype in typ.relevant_items()]
msg.disable_type_names -= 1
return UnionType.make_simplified_union(results)
elif isinstance(typ, TupleType):
# Actually look up from the fallback instance type.
return analyze_member_access(name, typ.fallback, node, is_lvalue, is_super,
is_operator, builtin_type, not_ready_callback, msg,
original_type=original_type, chk=chk)
elif isinstance(typ, TypedDictType):
# Actually look up from the fallback instance type.
return analyze_member_access(name, typ.fallback, node, is_lvalue, is_super,
is_operator, builtin_type, not_ready_callback, msg,
original_type=original_type, chk=chk)
elif isinstance(typ, FunctionLike) and typ.is_type_obj():
# Class attribute.
# TODO super?
ret_type = typ.items()[0].ret_type
if isinstance(ret_type, TupleType):
ret_type = ret_type.fallback
if isinstance(ret_type, Instance):
if not is_operator:
# When Python sees an operator (eg `3 == 4`), it automatically translates that
# into something like `int.__eq__(3, 4)` instead of `(3).__eq__(4)` as an
# optimization.
#
# While it normally it doesn't matter which of the two versions are used, it
# does cause inconsistencies when working with classes. For example, translating
# `int == int` to `int.__eq__(int)` would not work since `int.__eq__` is meant to
# compare two int _instances_. What we really want is `type(int).__eq__`, which
# is meant to compare two types or classes.
#
# This check makes sure that when we encounter an operator, we skip looking up
# the corresponding method in the current instance to avoid this edge case.
# See https://github.com/python/mypy/pull/1787 for more info.
result = analyze_class_attribute_access(ret_type, name, node, is_lvalue,
builtin_type, not_ready_callback, msg,
original_type=original_type)
if result:
return result
# Look up from the 'type' type.
return analyze_member_access(name, typ.fallback, node, is_lvalue, is_super,
is_operator, builtin_type, not_ready_callback, msg,
original_type=original_type, chk=chk)
else:
assert False, 'Unexpected type {}'.format(repr(ret_type))
elif isinstance(typ, FunctionLike):
# Look up from the 'function' type.
return analyze_member_access(name, typ.fallback, node, is_lvalue, is_super,
is_operator, builtin_type, not_ready_callback, msg,
original_type=original_type, chk=chk)
elif isinstance(typ, TypeVarType):
return analyze_member_access(name, typ.upper_bound, node, is_lvalue, is_super,
is_operator, builtin_type, not_ready_callback, msg,
original_type=original_type, chk=chk)
elif isinstance(typ, DeletedType):
msg.deleted_as_rvalue(typ, node)
return AnyType(TypeOfAny.from_error)
elif isinstance(typ, TypeType):
# Similar to FunctionLike + is_type_obj() above.
item = None
fallback = builtin_type('builtins.type')
ignore_messages = msg.copy()
ignore_messages.disable_errors()
if isinstance(typ.item, Instance):
item = typ.item
elif isinstance(typ.item, AnyType):
return analyze_member_access(name, fallback, node, is_lvalue, is_super,
is_operator, builtin_type, not_ready_callback,
ignore_messages, original_type=original_type, chk=chk)
elif isinstance(typ.item, TypeVarType):
if isinstance(typ.item.upper_bound, Instance):
item = typ.item.upper_bound
elif isinstance(typ.item, TupleType):
item = typ.item.fallback
elif isinstance(typ.item, FunctionLike) and typ.item.is_type_obj():
item = typ.item.fallback
elif isinstance(typ.item, TypeType):
# Access member on metaclass object via Type[Type[C]]
if isinstance(typ.item.item, Instance):
item = typ.item.item.type.metaclass_type
if item and not is_operator:
# See comment above for why operators are skipped
result = analyze_class_attribute_access(item, name, node, is_lvalue,
builtin_type, not_ready_callback, msg,
original_type=original_type)
if result:
if not (isinstance(result, AnyType) and item.type.fallback_to_any):
return result
else:
# We don't want errors on metaclass lookup for classes with Any fallback
msg = ignore_messages
if item is not None:
fallback = item.type.metaclass_type or fallback
return analyze_member_access(name, fallback, node, is_lvalue, is_super,
is_operator, builtin_type, not_ready_callback, msg,
original_type=original_type, chk=chk)
if chk.should_suppress_optional_error([typ]):
return AnyType(TypeOfAny.from_error)
return msg.has_no_attr(original_type, typ, name, node)
