Replace type comments with inline typing

src/marshmallow/fields.py

@@ -218,7 +218,7 @@ def __init__(
             )
 
         # Collect default error message from self and parent classes
-        messages = {}  # type: dict[str, str]
+        messages: dict[str, str] = {}
         for cls in reversed(self.__class__.__mro__):
             messages.update(getattr(cls, "default_error_messages", {}))
         messages.update(error_messages or {})
@@ -919,7 +919,7 @@ class Number(Field):
     :param kwargs: The same keyword arguments that :class:`Field` receives.
     """
 
-    num_type = float  # type: typing.Type
+    num_type: type = float
 
     #: Default error messages.
     default_error_messages = {
@@ -956,7 +956,7 @@ def _serialize(self, value, attr, obj, **kwargs) -> str | _T | None:
         """Return a string if `self.as_string=True`, otherwise return this field's `num_type`."""
         if value is None:
             return None
-        ret = self._format_num(value)  # type: _T
+        ret: _T = self._format_num(value)
         return self._to_string(ret) if self.as_string else ret
 
     def _deserialize(self, value, attr, data, **kwargs) -> _T | None:
@@ -1213,23 +1213,23 @@ class DateTime(Field):
         Add timestamp as a format.
     """
 
-    SERIALIZATION_FUNCS = {
+    SERIALIZATION_FUNCS: dict[str, typing.Callable[[typing.Any], str | float]] = {
         "iso": utils.isoformat,
         "iso8601": utils.isoformat,
         "rfc": utils.rfcformat,
         "rfc822": utils.rfcformat,
         "timestamp": utils.timestamp,
         "timestamp_ms": utils.timestamp_ms,
-    }  # type: dict[str, typing.Callable[[typing.Any], str | float]]
+    }
 
-    DESERIALIZATION_FUNCS = {
+    DESERIALIZATION_FUNCS: dict[str, typing.Callable[[str], typing.Any]] = {
         "iso": utils.from_iso_datetime,
         "iso8601": utils.from_iso_datetime,
         "rfc": utils.from_rfc,
         "rfc822": utils.from_rfc,
         "timestamp": utils.from_timestamp,
         "timestamp_ms": utils.from_timestamp_ms,
-    }  # type: dict[str, typing.Callable[[str], typing.Any]]
+    }
 
     DEFAULT_FORMAT = "iso"
 
@@ -1732,7 +1732,7 @@ class IP(Field):
 
     default_error_messages = {"invalid_ip": "Not a valid IP address."}
 
-    DESERIALIZATION_CLASS = None  # type: typing.Optional[typing.Type]
+    DESERIALIZATION_CLASS: type | None = None
 
     def __init__(self, *args, exploded=False, **kwargs):
         super().__init__(*args, **kwargs)
@@ -1796,7 +1796,7 @@ class IPInterface(Field):
 
     default_error_messages = {"invalid_ip_interface": "Not a valid IP interface."}
 
-    DESERIALIZATION_CLASS = None  # type: typing.Optional[typing.Type]
+    DESERIALIZATION_CLASS: type | None = None
 
     def __init__(self, *args, exploded: bool = False, **kwargs):
         super().__init__(*args, **kwargs)

src/marshmallow/schema.py

@@ -154,7 +154,7 @@ def resolve_hooks(cls) -> dict[str, list[tuple[str, bool, dict]]]:
         """
         mro = inspect.getmro(cls)
 
-        hooks = defaultdict(list)  # type: dict[str, list[tuple[str, bool, dict]]]
+        hooks: dict[str, list[tuple[str, bool, dict]]] = defaultdict(list)
 
         for attr_name in dir(cls):
             # Need to look up the actual descriptor, not whatever might be
@@ -174,7 +174,9 @@ def resolve_hooks(cls) -> dict[str, list[tuple[str, bool, dict]]]:
                 continue
 
             try:
-                hook_config = attr.__marshmallow_hook__  # type: dict[str, list[tuple[bool, dict]]]
+                hook_config: dict[str, list[tuple[bool, dict]]] = (
+                    attr.__marshmallow_hook__
+                )
             except AttributeError:
                 pass
             else:
@@ -282,7 +284,7 @@ class AlbumSchema(Schema):
         `prefix` parameter removed.
     """
 
-    TYPE_MAPPING = {
+    TYPE_MAPPING: dict[type, type[ma_fields.Field]] = {
         str: ma_fields.String,
         bytes: ma_fields.String,
         dt.datetime: ma_fields.DateTime,
@@ -297,23 +299,23 @@ class AlbumSchema(Schema):
         dt.date: ma_fields.Date,
         dt.timedelta: ma_fields.TimeDelta,
         decimal.Decimal: ma_fields.Decimal,
-    }  # type: dict[type, typing.Type[ma_fields.Field]]
+    }
     #: Overrides for default schema-level error messages
-    error_messages = {}  # type: dict[str, str]
+    error_messages: dict[str, str] = {}
 
-    _default_error_messages = {
+    _default_error_messages: dict[str, str] = {
         "type": "Invalid input type.",
         "unknown": "Unknown field.",
-    }  # type: dict[str, str]
+    }
 
-    OPTIONS_CLASS = SchemaOpts  # type: type
+    OPTIONS_CLASS: type = SchemaOpts
 
     set_class = OrderedSet
 
     # These get set by SchemaMeta
-    opts = None  # type: SchemaOpts
-    _declared_fields = {}  # type: dict[str, ma_fields.Field]
-    _hooks = {}  # type: dict[str, list[tuple[str, bool, dict]]]
+    opts: SchemaOpts
+    _declared_fields: dict[str, ma_fields.Field] = {}
+    _hooks: dict[str, list[tuple[str, bool, dict]]] = {}
 
     class Meta:
         """Options object for a Schema.
@@ -391,9 +393,9 @@ def __init__(
         self.context = context or {}
         self._normalize_nested_options()
         #: Dictionary mapping field_names -> :class:`Field` objects
-        self.fields = {}  # type: dict[str, ma_fields.Field]
-        self.load_fields = {}  # type: dict[str, ma_fields.Field]
-        self.dump_fields = {}  # type: dict[str, ma_fields.Field]
+        self.fields: dict[str, ma_fields.Field] = {}
+        self.load_fields: dict[str, ma_fields.Field] = {}
+        self.dump_fields: dict[str, ma_fields.Field] = {}
         self._init_fields()
         messages = {}
         messages.update(self._default_error_messages)
@@ -821,7 +823,7 @@ def _do_load(
         :return: Deserialized data
         """
         error_store = ErrorStore()
-        errors = {}  # type: dict[str, list[str]]
+        errors: dict[str, list[str]] = {}
         many = self.many if many is None else bool(many)
         unknown = (
             self.unknown
@@ -838,7 +840,7 @@ def _do_load(
                 )
             except ValidationError as err:
                 errors = err.normalized_messages()
-                result = None  # type: list | dict | None
+                result: list | dict | None = None
         else:
             processed_data = data
         if not errors:

src/marshmallow/validate.py

@@ -22,7 +22,7 @@ class Validator(ABC):
         add a useful `__repr__` implementation for validators.
     """
 
-    error = None  # type: str | None
+    error: str | None = None
 
     def __repr__(self) -> str:
         args = self._repr_args()
@@ -65,7 +65,7 @@ def is_even(value):
 
     def __init__(self, *validators: types.Validator, error: str | None = None):
         self.validators = tuple(validators)
-        self.error = error or self.default_error_message  # type: str
+        self.error: str = error or self.default_error_message
 
     def _repr_args(self) -> str:
         return f"validators={self.validators!r}"
@@ -191,7 +191,7 @@ def __init__(
             )
         self.relative = relative
         self.absolute = absolute
-        self.error = error or self.default_message  # type: str
+        self.error: str = error or self.default_message
         self.schemes = schemes or self.default_schemes
         self.require_tld = require_tld
 
@@ -250,7 +250,7 @@ class Email(Validator):
     default_message = "Not a valid email address."
 
     def __init__(self, *, error: str | None = None):
-        self.error = error or self.default_message  # type: str
+        self.error: str = error or self.default_message
 
     def _format_error(self, value: str) -> str:
         return self.error.format(input=value)
@@ -436,7 +436,7 @@ class Equal(Validator):
 
     def __init__(self, comparable, *, error: str | None = None):
         self.comparable = comparable
-        self.error = error or self.default_message  # type: str
+        self.error: str = error or self.default_message
 
     def _repr_args(self) -> str:
         return f"comparable={self.comparable!r}"
@@ -477,7 +477,7 @@ def __init__(
         self.regex = (
             re.compile(regex, flags) if isinstance(regex, (str, bytes)) else regex
         )
-        self.error = error or self.default_message  # type: str
+        self.error: str = error or self.default_message
 
     def _repr_args(self) -> str:
         return f"regex={self.regex!r}"
@@ -514,7 +514,7 @@ class Predicate(Validator):
 
     def __init__(self, method: str, *, error: str | None = None, **kwargs):
         self.method = method
-        self.error = error or self.default_message  # type: str
+        self.error: str = error or self.default_message
         self.kwargs = kwargs
 
     def _repr_args(self) -> str:
@@ -545,7 +545,7 @@ class NoneOf(Validator):
     def __init__(self, iterable: typing.Iterable, *, error: str | None = None):
         self.iterable = iterable
         self.values_text = ", ".join(str(each) for each in self.iterable)
-        self.error = error or self.default_message  # type: str
+        self.error: str = error or self.default_message
 
     def _repr_args(self) -> str:
         return f"iterable={self.iterable!r}"
@@ -585,7 +585,7 @@ def __init__(
         self.choices_text = ", ".join(str(choice) for choice in self.choices)
         self.labels = labels if labels is not None else []
         self.labels_text = ", ".join(str(label) for label in self.labels)
-        self.error = error or self.default_message  # type: str
+        self.error: str = error or self.default_message
 
     def _repr_args(self) -> str:
         return f"choices={self.choices!r}, labels={self.labels!r}"

tests/base.py

@@ -180,7 +180,7 @@ def get_lowername(obj):
 
 class UserSchema(Schema):
     name = fields.String()
-    age = fields.Float()  # type: fields.Field
+    age: fields.Field = fields.Float()
     created = fields.DateTime()
     created_formatted = fields.DateTime(
         format="%Y-%m-%d", attribute="created", dump_only=True
@@ -193,7 +193,7 @@ class UserSchema(Schema):
     homepage = fields.Url()
     email = fields.Email()
     balance = fields.Decimal()
-    is_old = fields.Method("get_is_old")  # type: fields.Field
+    is_old: fields.Field = fields.Method("get_is_old")
     lowername = fields.Function(get_lowername)
     registered = fields.Boolean()
     hair_colors = fields.List(fields.Raw)