Allow "patch()" to be called multiple times on same logger (#462)

CHANGELOG.rst

@@ -1,3 +1,9 @@
+`Unreleased`_
+=============
+
+- Make ``patch()`` calls cumulative instead of overriding the possibly existing patching function (`#462 <https://github.com/Delgan/loguru/issues/462>`_).
+
+
 `0.6.0`_ (2022-01-29)
 =====================
 

loguru/__init__.py

@@ -23,7 +23,7 @@
     colors=False,
     raw=False,
     capture=True,
-    patcher=None,
+    patchers=[],
     extra={},
 )
 

loguru/_logger.py

@@ -95,7 +95,13 @@
 from ._get_frame import get_frame
 from ._handler import Handler
 from ._locks_machinery import create_logger_lock
-from ._recattrs import RecordException, RecordFile, RecordLevel, RecordProcess, RecordThread
+from ._recattrs import (
+    RecordException,
+    RecordFile,
+    RecordLevel,
+    RecordProcess,
+    RecordThread,
+)
 from ._simple_sinks import AsyncSink, CallableSink, StandardSink, StreamSink
 
 if sys.version_info >= (3, 6):
@@ -209,9 +215,9 @@ class Logger:
     You should not instantiate a |Logger| by yourself, use ``from loguru import logger`` instead.
     """
 
-    def __init__(self, core, exception, depth, record, lazy, colors, raw, capture, patcher, extra):
+    def __init__(self, core, exception, depth, record, lazy, colors, raw, capture, patchers, extra):
         self._core = core
-        self._options = (exception, depth, record, lazy, colors, raw, capture, patcher, extra)
+        self._options = (exception, depth, record, lazy, colors, raw, capture, patchers, extra)
 
     def __repr__(self):
         return "<loguru.logger handlers=%r>" % list(self._core.handlers.values())
@@ -1426,6 +1432,9 @@ def patch(self, patcher):
         ``record`` dict itself, as some values are used internally by `Loguru`, and modify them may
         produce unexpected results.
 
+        The logger can be patched multiple times. In this case, the functions are called in the
+        same order as they are added.
+
         Parameters
         ----------
         patcher: |callable|_
@@ -1457,8 +1466,8 @@ def patch(self, patcher):
         ...     level, message = record["level"], record["message"]
         ...     logger.patch(lambda r: r.update(record)).log(level, message)
         """
-        *options, _, extra = self._options
-        return Logger(self._core, *options, patcher, extra)
+        *options, patchers, extra = self._options
+        return Logger(self._core, *options, patchers + [patcher], extra)
 
     def level(self, name, no=None, color=None, icon=None):
         """Add, update or retrieve a logging level.
@@ -1853,7 +1862,7 @@ def _log(self, level_id, static_level_no, from_decorator, options, message, args
         if not core.handlers:
             return
 
-        (exception, depth, record, lazy, colors, raw, capture, patcher, extra) = options
+        (exception, depth, record, lazy, colors, raw, capture, patchers, extra) = options
 
         frame = get_frame(depth + 2)
 
@@ -1961,7 +1970,7 @@ def _log(self, level_id, static_level_no, from_decorator, options, message, args
         if core.patcher:
             core.patcher(log_record)
 
-        if patcher:
+        for patcher in patchers:
             patcher(log_record)
 
         for handler in core.handlers.values():

tests/conftest.py

@@ -8,9 +8,8 @@
 import traceback
 import warnings
 
-import pytest
-
 import loguru
+import pytest
 
 if sys.version_info < (3, 5, 3):
 
@@ -83,7 +82,7 @@ def reset_logger():
     def reset():
         loguru.logger.remove()
         loguru.logger.__init__(
-            loguru._logger.Core(), None, 0, False, False, False, False, True, None, {}
+            loguru._logger.Core(), None, 0, False, False, False, False, True, [], {}
         )
         loguru._logger.context.set({})
 

tests/test_patch.py

@@ -67,3 +67,19 @@ def test_override_configured(writer):
     logger2.debug("!")
 
     assert writer.read() == "456 678 !\n"
+
+
+def test_multiple_patches(writer):
+    def patch_1(record):
+        record["extra"]["a"] = 5
+
+    def patch_2(record):
+        record["extra"]["a"] += 1
+
+    def patch_3(record):
+        record["extra"]["a"] *= 2
+
+    logger.add(writer, format="{extra[a]} {message}")
+    logger.patch(patch_1).patch(patch_2).patch(patch_3).info("Test")
+
+    assert writer.read() == "12 Test\n"