From 890f8939fcd877eb44345192431bd7eb1145ac9b Mon Sep 17 00:00:00 2001
From: Simon-Martin Schroeder <sms@informatik.uni-kiel.de>
Date: Tue, 24 May 2022 16:33:13 +0200
Subject: [PATCH] feat(TrialLogHandler): Hook into Python's logging

---
 experitur/core/log_handler.py | 45 +++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 experitur/core/log_handler.py

diff --git a/experitur/core/log_handler.py b/experitur/core/log_handler.py
new file mode 100644
index 0000000..515b93e
--- /dev/null
+++ b/experitur/core/log_handler.py
@@ -0,0 +1,45 @@
+import logging
+
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from experitur.core.trial import Trial
+
+
+class TrialLogHandler(logging.Handler):
+    """
+    Hook into Python's logging to save entries in the trial log.
+    
+    Example:
+        with TrialLogHandler(trial):
+            ...
+    """
+
+    def __init__(self, trial: "Trial"):
+        super().__init__()
+        self.trial = trial
+
+    def emit(self, record):
+        """
+        Emit a record.
+
+        If a formatter is specified, it is used to format the record.
+        The record is then written to the stream with a trailing newline.  If
+        exception information is present, it is formatted using
+        traceback.print_exception and appended to the stream.  If the stream
+        has an 'encoding' attribute, it is used to determine how to do the
+        output to the stream.
+        """
+        try:
+            msg = self.format(record)
+            self.trial.log_msg(msg)
+        except RecursionError:
+            raise
+        except Exception:  # pylint: disable=broad-except
+            self.handleError(record)
+
+    def __enter__(self):
+        logging.root.addHandler(self)
+
+    def __exit__(self, *_, **__):
+        logging.root.removeHandler(self)