Auto apply dataclass decorator to subclasses

coqpit/coqpit.py

@@ -408,7 +408,7 @@ def deserialize(self, data: dict) -> "Serializable":
                 init_kwargs[field.name] = value
                 continue
             if value == MISSING:
-                raise ValueError("deserialized with unknown value for {} in {}".format(field.name, self.__name__))
+                raise ValueError(f"deserialized with unknown value for {field.name} in {self.__name__}")
             value = _deserialize(value, field.type)
             init_kwargs[field.name] = value
         for k, v in init_kwargs.items():
@@ -438,7 +438,7 @@ def deserialize_immutable(cls, data: dict) -> "Serializable":
                 init_kwargs[field.name] = value
                 continue
             if value == MISSING:
-                raise ValueError("Deserialized with unknown value for {} in {}".format(field.name, cls.__name__))
+                raise ValueError(f"Deserialized with unknown value for {field.name} in {cls.__name__}")
             value = _deserialize(value, field.type)
             init_kwargs[field.name] = value
         return cls(**init_kwargs)
@@ -578,6 +578,9 @@ class Coqpit(Serializable, MutableMapping):
 
     _initialized = False
 
+    def __init_subclass__(cls, **kwargs):
+        return dataclass(_cls=cls, **kwargs)
+
     def _is_initialized(self):
         """Check if Coqpit is initialized. Useful to prevent running some aux functions
         at the initialization when no attribute has been defined."""

tests/test_metaing.py

@@ -0,0 +1,10 @@
+import dataclasses
+from coqpit.coqpit import Coqpit
+
+
+class SimpleConstructConfig(Coqpit):
+    a: int = 20
+
+
+def test_copying():
+    assert dataclasses.is_dataclass(SimpleConstructConfig())