[clean strict optional] Fix more strict optional errors #3292
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mypy/checkmember.py
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| @@ -518,7 +520,7 @@ def type_object_type_from_function(init_or_new: FuncBase, info: TypeInfo, | |||
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| if init_or_new.info.fullname() == 'builtins.dict': | |||
| # Special signature! | |||
| special_sig = 'dict' | |||
| special_sig = 'dict' # type: Optional[str] | |||
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Honestly this would look better rewritten as
special_sig = None # type: Optional[str]
if <blah>:
special_sig = 'dict'
mypy/constraints.py
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| @@ -25,7 +25,7 @@ class Constraint: | |||
| It can be either T <: type or T :> type (T is a type variable). | |||
| """ | |||
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| type_var = None # Type variable id | |||
| type_var = None # type: TypeVarId # Type variable id | |||
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The rest of the comment seems pretty redundant now. :-)
mypy/exprtotype.py
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| @@ -52,6 +52,7 @@ def expr_to_unanalyzed_type(expr: Expression) -> Type: | |||
| result = parse_type_comment(expr.value, expr.line, None) | |||
| except SyntaxError: | |||
| raise TypeTranslationError() | |||
| assert result is not None | |||
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Could be moved closer to the assignment (inside the try block)?
mypy/meet.py
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| (item_name, s_item_type or t_item_type) | ||
| for (item_name, s_item_type, t_item_type) in self.s.zipall(t) | ||
| ]) | ||
| item_list = cast(List[Tuple[str, Type]], |
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I really don't like casts, and this one looks particularly scary given the complexity of what it's casting from. Suggestion:
item_list = [(item_name, s_item_type if s_item_type is not None else t_item_type)
for (item_name, s_item_type, t_item_type) in self.s.zipall(t)]] # type: List[str, Optional[Type]]
# Actually none of the items are None now,
# since at least one of s_item_type and t_item_type is not None
items = OrderedDict(cast(List[str, Type], items_list))
That's still a cast, but the comprehension gets type-checked.
Another alternative would built item_list is a good old-fashioned for-loop, with a declared type of List[str, Type], and an assert in the loop body that the item is not None.
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I would choose the second option (for-loop), the comprehension is a bit hard to read here.
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Thanks for review! I implemented all comments in the new commits. |
This PR makes
--strict-optionalclean for:Fixing annotations in nodes.py lead to few dozens new errors (reducing the net progress), mostly in fastparse.py, fastparse2.py, semanal.py, checker.py, checkexpr.py. Actually those files seem to be most "dirty" (in general, the type layer is much "cleaner" than the expression layer).
There are few observations about what features would be useful with
-strict-optional:Union[X, None]asOptioal[X]in errors, not something likesome element of union doesn't have attribute xorunsupported left type for + (some union)x = None # type: Xin functions (not only in classes). This could be fixed by PEP 526 syntax, but only in Python 3.6+x[i] is not None,x.attr is not None, andNone not in x(for collections).