Add a function to get a public logger for a module

src/frequenz/core/logging.py

@@ -0,0 +1,38 @@
+# License: MIT
+# Copyright © 2023 Frequenz Energy-as-a-Service GmbH
+
+"""Logging tools."""
+
+import logging
+
+
+def get_public_logger(module_name: str) -> logging.Logger:
+    """Get a logger for the public module containing the given module name.
+
+    * Modules are considered private if they start with `_`.
+    * All modules inside a private module are also considered private, even if they
+      don't start with `_`.
+    * If there is no leading public part, the root logger is returned.
+
+    Example:
+        Here are a few examples of how this function will resolve module names:
+
+        * `some.pub` -> `some.pub`
+        * `some.pub._some._priv` -> `some.pub`
+        * `some.pub._some._priv.public` -> `some.pub`
+        * `some.pub._some._priv.public._private` -> `some.pub`
+        * `_priv` -> `root`
+
+    Args:
+        module_name: The fully qualified name of the module to get the logger for
+            (normally the `__name__` built-in variable).
+
+    Returns:
+        The logger for the public module containing the given module name.
+    """
+    public_parts: list[str] = []
+    for part in module_name.split("."):
+        if part.startswith("_"):
+            break
+        public_parts.append(part)
+    return logging.getLogger(".".join(public_parts))

tests/test_logging.py

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+# License: MIT
+# Copyright © 2024 Frequenz Energy-as-a-Service GmbH
+
+"""Tests for the log module."""
+
+
+import pytest
+
+from frequenz.core.logging import get_public_logger
+
+
+@pytest.mark.parametrize(
+    "module_name, expected_logger_name",
+    [
+        ("some.pub", "some.pub"),
+        ("some.pub._some._priv", "some.pub"),
+        ("some.pub._some._priv.public", "some.pub"),
+        ("some.pub._some._priv.public._private", "some.pub"),
+        ("some._priv.pub", "some"),
+        ("_priv.some.pub", "root"),
+        ("some", "some"),
+        ("some._priv", "some"),
+        ("_priv", "root"),
+    ],
+)
+def test_get_public_logger(module_name: str, expected_logger_name: str) -> None:
+    """Test that the logger name is as expected."""
+    logger = get_public_logger(module_name)
+    assert logger.name == expected_logger_name