Split up default data adapters

With the change of applies_to -- it means
that single classes are not a good idea. So splitting
up the default ones appropriately.

hamilton/io/default_data_loaders.py

@@ -9,7 +9,7 @@
 
 
 @dataclasses.dataclass
-class JSONDataAdapter(DataLoader, DataSaver):
+class JSONDataLoader(DataLoader):
     path: str
 
     @classmethod
@@ -24,14 +24,27 @@ def load_data(self, type_: Type) -> Tuple[dict, Dict[str, Any]]:
     def name(cls) -> str:
         return "json"
 
+
+@dataclasses.dataclass
+class JSONDataSaver(DataSaver):
+    path: str
+
+    @classmethod
+    def applicable_types(cls) -> Collection[Type]:
+        return [dict]
+
+    @classmethod
+    def name(cls) -> str:
+        return "json"
+
     def save_data(self, data: Any) -> Dict[str, Any]:
         with open(self.path, "w") as f:
             json.dump(data, f)
         return get_file_metadata(self.path)
 
 
 @dataclasses.dataclass
-class RawFileDataLoader(DataLoader, DataSaver):
+class RawFileDataLoader(DataLoader):
     path: str
     encoding: str = "utf-8"
 
@@ -47,6 +60,20 @@ def applicable_types(cls) -> Collection[Type]:
     def name(cls) -> str:
         return "file"
 
+
+@dataclasses.dataclass
+class RawFileDataSaver(DataSaver):
+    path: str
+    encoding: str = "utf-8"
+
+    @classmethod
+    def applicable_types(cls) -> Collection[Type]:
+        return [str]
+
+    @classmethod
+    def name(cls) -> str:
+        return "file"
+
     def save_data(self, data: Any) -> Dict[str, Any]:
         with open(self.path, "w", encoding=self.encoding) as f:
             f.write(data)
@@ -65,10 +92,23 @@ def applicable_types(cls) -> Collection[Type]:
     def name(cls) -> str:
         return "pickle"
 
-    def load_data(self, type_: Type[dict]) -> Tuple[str, Dict[str, Any]]:
+    def load_data(self, type_: Type[object]) -> Tuple[object, Dict[str, Any]]:
         with open(self.path, "rb") as f:
             return pickle.load(f), get_file_metadata(self.path)
 
+
+@dataclasses.dataclass
+class PickleSaver(DataSaver):
+    path: str
+
+    @classmethod
+    def applicable_types(cls) -> Collection[Type]:
+        return [object]
+
+    @classmethod
+    def name(cls) -> str:
+        return "pickle"
+
     def save_data(self, data: Any) -> Dict[str, Any]:
         with open(self.path, "wb") as f:
             pickle.dump(data, f)
@@ -127,10 +167,13 @@ def name(cls) -> str:
 
 
 DATA_ADAPTERS = [
-    JSONDataAdapter,
+    JSONDataSaver,
+    JSONDataLoader,
     LiteralValueDataLoader,
     RawFileDataLoader,
+    RawFileDataSaver,
     PickleLoader,
+    PickleSaver,
     EnvVarDataLoader,
     InMemoryResult,
 ]