Declare literal_hash as Optional[Key] #3658
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mypy/binder.py
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| @@ -15,7 +15,7 @@ | |||
| BindableExpression = Union[IndexExpr, MemberExpr, NameExpr] | |||
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| class Frame(Dict[Key, Type]): | |||
| class Frame(Dict[Optional[Key], Type]): | |||
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Does the base class really have to use Optional[Key] as its key type? Does None really occur as a valid key?
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You can't just remove the Optional here. I'm not sure that the value actually occurs (it does not make much sense to me), but the type is used in 5 different places*,
I tried to avoid adding if key is not None to keep the change minimal.
(*) lines 109, 116, 151, 270, 271
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I think the actual semantics is that keys should not be None. Therefore it should not be Optional here. Also, saving few lines of code does not justify adding potentially misleading hints. Strict optional typically touches subtle things, thus everything should be written as "right" as possible.
mypy/binder.py
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| @@ -15,7 +15,7 @@ | |||
| BindableExpression = Union[IndexExpr, MemberExpr, NameExpr] | |||
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| class Frame(Dict[Key, Type]): | |||
| class Frame(Dict[Optional[Key], Type]): | |||
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I think the actual semantics is that keys should not be None. Therefore it should not be Optional here. Also, saving few lines of code does not justify adding potentially misleading hints. Strict optional typically touches subtle things, thus everything should be written as "right" as possible.
mypy/binder.py
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| @@ -31,7 +31,7 @@ def __init__(self) -> None: | |||
| self.unreachable = False | |||
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| class DeclarationsFrame(Dict[Key, Optional[Type]]): | |||
| class DeclarationsFrame(Dict[Optional[Key], Optional[Type]]): | |||
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This Optional is also not needed IMO.
mypy/binder.py
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| @@ -125,7 +125,8 @@ def put(self, expr: Expression, typ: Type) -> None: | |||
| if key not in self.declarations: | |||
| assert isinstance(expr, BindableTypes) | |||
| self.declarations[key] = get_declaration(expr) | |||
| self._add_dependencies(key) | |||
| if key is not None: | |||
| self._add_dependencies(key) | |||
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This change actually looks reasonable.
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I cannot comment there, but you can just add similar things for return self._get(expr.literal_hash) etc., or assert expr.literal_hash is not None where appropriate.
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Maybe it's better to simply initialize the field to |
mypy/binder.py
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| @@ -122,6 +122,7 @@ def put(self, expr: Expression, typ: Type) -> None: | |||
| if not expr.literal: | |||
| return | |||
| key = expr.literal_hash | |||
| assert key is not None | |||
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I would prefer to see a descriptive assertion message here, maybe "Internal error: binder tried to put non-literal", ditto for get and cleanse.
literal_hash = None # type: Keyis an actual initialization and the None value is accessed, so it should be declared that way. Strict-optional mode does not catch it since it looks like a declaration.(Surfaced in #3071 here)