extract dataclass-based config helper

my/core/cfg.py

@@ -0,0 +1,18 @@
+from typing import TypeVar, Type, Callable, Dict, Any
+
+Attrs = Dict[str, Any]
+
+C = TypeVar('C')
+
+# todo not sure about it, could be overthinking...
+# but short enough to change later
+def make_config(cls: Type[C], migration: Callable[[Attrs], Attrs]=lambda x: x) -> C:
+    props = dict(vars(cls.__base__))
+    props = migration(props)
+    from dataclasses import fields
+    params = {
+        k: v
+        for k, v in props.items()
+        if k in {f.name for f in fields(cls)}
+    }
+    return cls(**params) # type: ignore[call-arg]