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#4897: allow raise E where E: Type[Exn] #4918

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Merged
ilevkivskyi merged 4 commits into from
May 15, 2018
Merged

#4897: allow raise E where E: Type[Exn] #4918

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4326c26
allow `raise E` where E: Type[Exn]
Apr 16, 2018
dc2a7a7
add negative test
Apr 16, 2018
c2ad1d5
extract type from `TypeType` and proceed as normal
Apr 17, 2018
9e09e7a
you can catch with Type[E] too
May 15, 2018
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4 changes: 4 additions & 0 deletions mypy/checker.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2357,6 +2357,10 @@ def visit_raise_stmt(self, s: RaiseStmt) -> None:
def type_check_raise(self, e: Expression, s: RaiseStmt,
optional: bool = False) -> None:
typ = self.expr_checker.accept(e)
if isinstance(typ, TypeType):
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@ilevkivskyi ilevkivskyi Apr 22, 2018

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Shouldn't (for consistency) the same case be added to check_except_handler_test (with test cases)?

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@bwo bwo May 15, 2018

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if you mean that this should work:

[case testExceptWithTypeType]
import typing
E = BaseException  # type: typing.Type[BaseException]

try:
    pass
except E:
    pass
[builtins fixtures/exception.pyi]

it already does, though I can certainly add that test.

if isinstance(typ.item, AnyType):
return
typ = typ.item
if isinstance(typ, FunctionLike):
if typ.is_type_obj():
# Cases like "raise/from ExceptionClass".
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24 changes: 22 additions & 2 deletions test-data/unit/check-statements.test
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Expand Up @@ -410,8 +410,19 @@ raise object # E: Exception must be derived from BaseException
raise f # E: Exception must be derived from BaseException
[builtins fixtures/exception.pyi]

[case testRaiseFromStatement]
[case testRaiseExceptionType]
import typing
x = None # type: typing.Type[BaseException]
raise x
[builtins fixtures/exception.pyi]

[case testRaiseNonExceptionTypeFails]
import typing
x = int # type: typing.Type[int]
raise x # E: Exception must be derived from BaseException
[builtins fixtures/exception.pyi]

[case testRaiseFromStatement]
e = None # type: BaseException
f = None # type: MyError
a = None # type: A
Expand Down Expand Up @@ -628,6 +639,16 @@ except ((E1, E2)): pass
except (((E1, E2))): pass
[builtins fixtures/exception.pyi]

[case testExceptWithTypeType]
import typing
E = BaseException # type: typing.Type[BaseException]

try:
pass
except E:
pass
[builtins fixtures/exception.pyi]

[case testExceptWithMultipleTypes2]
import typing
class E1(BaseException): pass
Expand Down Expand Up @@ -1615,4 +1636,3 @@ N = TypedDict('N', {'x': int})
[builtins fixtures/dict.pyi]
[typing fixtures/typing-full.pyi]
[out]