Improve typing.

dash/_callback.py

@@ -77,7 +77,7 @@ def callback(
     cache_ignore_triggered=True,
     on_error: Optional[Callable[[Exception], Any]] = None,
     **_kwargs,
-):
+) -> Callable[..., Any]:
     """
     Normally used as a decorator, `@dash.callback` provides a server-side
     callback relating the values of one or more `Output` items to one or

dash/dash.py

@@ -1269,7 +1269,7 @@ def clientside_callback(self, clientside_function, *args, **kwargs):
             **kwargs,
         )
 
-    def callback(self, *_args, **_kwargs):
+    def callback(self, *_args, **_kwargs) -> Callable[..., Any]:
         """
         Normally used as a decorator, `@app.callback` provides a server-side
         callback relating the values of one or more `Output` items to one or

dash/dependencies.py

@@ -1,12 +1,17 @@
+from typing import Union, Sequence
+
 from dash.development.base_component import Component
 
 from ._validate import validate_callback
 from ._grouping import flatten_grouping, make_grouping_by_index
 from ._utils import stringify_id
 
 
+ComponentIdType = Union[str, Component, dict]
+
+
 class _Wildcard:  # pylint: disable=too-few-public-methods
-    def __init__(self, name):
+    def __init__(self, name: str):
         self._name = name
 
     def __str__(self):
@@ -15,7 +20,7 @@ def __str__(self):
     def __repr__(self):
         return f"<{self}>"
 
-    def to_json(self):
+    def to_json(self) -> str:
         # used in serializing wildcards - arrays are not allowed as
         # id values, so make the wildcards look like length-1 arrays.
         return f'["{self._name}"]'
@@ -27,7 +32,12 @@ def to_json(self):
 
 
 class DashDependency:  # pylint: disable=too-few-public-methods
-    def __init__(self, component_id, component_property):
+    component_id: ComponentIdType
+    allow_duplicate: bool
+    component_property: str
+    allowed_wildcards: Sequence[_Wildcard]
+
+    def __init__(self, component_id: ComponentIdType, component_property: str):
 
         if isinstance(component_id, Component):
             self.component_id = component_id._set_random_id()
@@ -43,10 +53,10 @@ def __str__(self):
     def __repr__(self):
         return f"<{self.__class__.__name__} `{self}`>"
 
-    def component_id_str(self):
+    def component_id_str(self) -> str:
         return stringify_id(self.component_id)
 
-    def to_dict(self):
+    def to_dict(self) -> dict:
         return {"id": self.component_id_str(), "property": self.component_property}
 
     def __eq__(self, other):
@@ -61,7 +71,7 @@ def __eq__(self, other):
             and self._id_matches(other)
         )
 
-    def _id_matches(self, other):
+    def _id_matches(self, other) -> bool:
         my_id = self.component_id
         other_id = other.component_id
         self_dict = isinstance(my_id, dict)
@@ -96,7 +106,7 @@ def _id_matches(self, other):
     def __hash__(self):
         return hash(str(self))
 
-    def has_wildcard(self):
+    def has_wildcard(self) -> bool:
         """
         Return true if id contains a wildcard (MATCH, ALL, or ALLSMALLER)
         """
@@ -112,7 +122,12 @@ class Output(DashDependency):  # pylint: disable=too-few-public-methods
 
     allowed_wildcards = (MATCH, ALL)
 
-    def __init__(self, component_id, component_property, allow_duplicate=False):
+    def __init__(
+        self,
+        component_id: ComponentIdType,
+        component_property: str,
+        allow_duplicate: bool = False,
+    ):
         super().__init__(component_id, component_property)
         self.allow_duplicate = allow_duplicate
 
@@ -130,7 +145,7 @@ class State(DashDependency):  # pylint: disable=too-few-public-methods
 
 
 class ClientsideFunction:  # pylint: disable=too-few-public-methods
-    def __init__(self, namespace=None, function_name=None):
+    def __init__(self, namespace: str, function_name: str):
 
         if namespace.startswith("_dashprivate_"):
             raise ValueError("Namespaces cannot start with '_dashprivate_'.")

dash/development/_py_components_generation.py

@@ -24,7 +24,7 @@
 import typing  # noqa: F401
 import numbers # noqa: F401
 from typing_extensions import TypedDict, NotRequired, Literal # noqa: F401
-from dash.development.base_component import Component, _explicitize_args
+from dash.development.base_component import Component
 try:
     from dash.development.base_component import ComponentType # noqa: F401
 except ImportError:
@@ -80,7 +80,8 @@ def generate_class_string(
     _namespace = '{namespace}'
     _type = '{typename}'
 {shapes}
-    @_explicitize_args
+    _explicitize_dash_init = True
+
     def __init__(
         self,
         {default_argtext}

dash/development/base_component.py

@@ -51,13 +51,21 @@ class ComponentMeta(abc.ABCMeta):
 
     # pylint: disable=arguments-differ
     def __new__(mcs, name, bases, attributes):
-        component = abc.ABCMeta.__new__(mcs, name, bases, attributes)
         module = attributes["__module__"].split(".")[0]
+
+        if attributes.get("_explicitize_dash_init", False):
+            # We only want to patch the new generated component without
+            # the `@_explicitize_args` decorator for mypy support
+            # See issue: https://github.com/plotly/dash/issues/3226
+            attributes["__init__"] = _explicitize_args(attributes["__init__"])
+
+        _component = abc.ABCMeta.__new__(mcs, name, bases, attributes)
+
         if name == "Component" or module == "builtins":
-            # Don't do the base component
+            # Don't add to the registry the base component
             # and the components loaded dynamically by load_component
             # as it doesn't have the namespace.
-            return component
+            return _component
 
         _namespace = attributes.get("_namespace", module)
         ComponentRegistry.namespace_to_package[_namespace] = module
@@ -66,7 +74,7 @@ def __new__(mcs, name, bases, attributes):
             "_children_props"
         )
 
-        return component
+        return _component
 
 
 def is_number(s):
@@ -435,6 +443,8 @@ def _validate_deprecation(self):
 
 ComponentType = typing.TypeVar("ComponentType", bound=Component)
 
+ComponentTemplate = typing.TypeVar("ComponentTemplate")
+
 
 # This wrapper adds an argument given to generated Component.__init__
 # with the actual given parameters by the user as a list of string.

requirements/ci.txt

@@ -18,4 +18,4 @@ pyzmq==25.1.2
 xlrd>=2.0.1
 pytest-rerunfailures
 jupyterlab<4.0.0
-pyright==1.1.376;python_version>="3.7"
+pyright==1.1.398;python_version>="3.7"

tests/integration/test_typing.py

@@ -223,15 +223,17 @@ def assert_pyright_output(
             "obj={}",
             {
                 "expected_status": 1,
-                "expected_outputs": ['"dict[Any, Any]" is incompatible with "Obj"'],
+                "expected_outputs": [
+                    '"dict[Any, Any]" cannot be assigned to parameter "obj" of type "Obj | None"'
+                ],
             },
         ),
         (
             "obj={'value': 'a', 'label': 1}",
             {
                 "expected_status": 1,
                 "expected_outputs": [
-                    '"dict[str, str | int]" is incompatible with "Obj"'
+                    '"dict[str, str | int]" cannot be assigned to parameter "obj" of type "Obj | None"'
                 ],
             },
         ),

tests/unit/development/metadata_test.py

@@ -3,7 +3,7 @@
 import typing  # noqa: F401
 import numbers # noqa: F401
 from typing_extensions import TypedDict, NotRequired, Literal # noqa: F401
-from dash.development.base_component import Component, _explicitize_args
+from dash.development.base_component import Component
 try:
     from dash.development.base_component import ComponentType # noqa: F401
 except ImportError:
@@ -131,7 +131,8 @@ class Table(Component):
         }
     )
 
-    @_explicitize_args
+    _explicitize_dash_init = True
+
     def __init__(
         self,
         children: typing.Optional[typing.Union[str, int, float, ComponentType, typing.Sequence[typing.Union[str, int, float, ComponentType]]]] = None,