rename

eta/common.py

@@ -0,0 +1,32 @@
+from __future__ import annotations
+from dataclasses import dataclass
+from os import environ
+from typing import TypeAlias
+
+
+JSONDataScalar: TypeAlias = str | None | float | bool
+JSONDataList: TypeAlias = list["JSONDataScalar | JSONDataMap | JSONDataList"]
+JSONDataMap: TypeAlias = dict[str, "JSONDataScalar | JSONDataList | JSONDataMap"]
+JSONData: TypeAlias = "JSONDataMap | JSONDataList"
+
+
+@dataclass
+class EnvVar:
+    """
+    Environment Variable fetcher for use in dataclass ``field(default_factory=...)``
+
+    >>> @dataclass
+    >>> class SomeDataclass:
+    ...     field_name: str = field(default_factory=EnvVar("SOME_VAR_NAME", "err msg"))
+
+    """
+
+    var_name: str
+    err_msg: str = ""
+
+    def __call__(self) -> str:
+        try:
+            return environ[self.var_name]
+        except KeyError as e:
+            e.add_note(self.err_msg)
+            raise