add configs to validate_arguments (#1378)

* add `configs` to validate_arguments

* simplify `validate_arguments` and add annotation for parameter `configs`

* change double quotes to single quotes

* reformat code

* fix mypy error

* fix mypy 'maximum semantic analysis' error

* rename 'configs' > 'config_params'

Co-authored-by: Samuel Colvin <s@muelcolvin.com>

pydantic/decorator.py

@@ -14,20 +14,27 @@ if TYPE_CHECKING:
     Callable = TypeVar('Callable', bound=AnyCallable)
 
 
-def validate_arguments(function: 'Callable') -> 'Callable':
+def validate_arguments(func: 'Callable' = None, **config_params: Any) -> 'Callable':
     """
     Decorator to validate the arguments passed to a function.
     """
-    vd = ValidatedFunction(function)
 
-    @wraps(function)
-    def wrapper_function(*args: Any, **kwargs: Any) -> Any:
-        return vd.call(*args, **kwargs)
+    def validate(_func: 'Callable') -> 'Callable':
+        vd = ValidatedFunction(_func, **config_params)
 
-    wrapper_function.vd = vd  # type: ignore
-    wrapper_function.raw_function = vd.raw_function  # type: ignore
-    wrapper_function.model = vd.model  # type: ignore
-    return cast('Callable', wrapper_function)
+        @wraps(_func)
+        def wrapper_function(*args: Any, **kwargs: Any) -> Any:
+            return vd.call(*args, **kwargs)
+
+        wrapper_function.vd = vd  # type: ignore
+        wrapper_function.raw_function = vd.raw_function  # type: ignore
+        wrapper_function.model = vd.model  # type: ignore
+        return cast('Callable', wrapper_function)
+
+    if func:
+        return validate(func)
+    else:
+        return cast('Callable', validate)
 
 
 ALT_V_ARGS = 'v__args'
@@ -36,7 +43,7 @@ V_POSITIONAL_ONLY_NAME = 'v__positional_only'
 
 
 class ValidatedFunction:
-    def __init__(self, function: 'Callable'):
+    def __init__(self, function: 'Callable', **config_params: Any):
         from inspect import signature, Parameter
 
         parameters: Mapping[str, Parameter] = signature(function).parameters
@@ -100,7 +107,7 @@ class ValidatedFunction:
             # same with kwargs
             fields[self.v_kwargs_name] = Dict[Any, Any], None
 
-        self.create_model(fields, takes_args, takes_kwargs)
+        self.create_model(fields, takes_args, takes_kwargs, **config_params)
 
     def call(self, *args: Any, **kwargs: Any) -> Any:
         values = self.build_values(args, kwargs)
@@ -170,9 +177,17 @@ class ValidatedFunction:
         else:
             return self.raw_function(**d)
 
-    def create_model(self, fields: Dict[str, Any], takes_args: bool, takes_kwargs: bool) -> None:
+    def create_model(self, fields: Dict[str, Any], takes_args: bool, takes_kwargs: bool, **config_params: Any) -> None:
         pos_args = len(self.arg_mapping)
 
+        if TYPE_CHECKING:
+
+            class CustomConfig:
+                pass
+
+        else:
+            CustomConfig = type('Config', (), config_params)
+
         class DecoratorBaseModel(BaseModel):
             @validator(self.v_args_name, check_fields=False, allow_reuse=True)
             def check_args(cls, v: List[Any]) -> List[Any]:
@@ -196,7 +211,7 @@ class ValidatedFunction:
                 keys = ', '.join(map(repr, v))
                 raise TypeError(f'positional-only argument{plural} passed as keyword argument{plural}: {keys}')
 
-            class Config:
+            class Config(CustomConfig):
                 extra = Extra.forbid
 
         self.model = create_model(to_camel(self.raw_function.__name__), __base__=DecoratorBaseModel, **fields)