Merge pull request #18 from dastels/master

Null Logger

Author: brentru

adafruit_logging.py

@@ -95,28 +95,35 @@ def emit(self, level, msg):
 # pylint:disable=undefined-variable
 
 logger_cache = dict()
+null_logger = None
 
-
+# pylint:disable=global-statement
 def getLogger(name):
     """Create or retrieve a logger by name.
 
-    :param name: the name of the logger to create/retrieve
+    :param name: the name of the logger to create/retrieve None will cause the
+                 NullLogger instance to be returned.
 
     """
+    global null_logger
+    if not name or name == "":
+        if not null_logger:
+            null_logger = NullLogger()
+        return null_logger
+
     if name not in logger_cache:
         logger_cache[name] = Logger()
     return logger_cache[name]
 
 
+# pylint:enable=global-statement
+
+
 class Logger:
     """Provide a logging api."""
 
     def __init__(self):
-        """Create an instance.
-
-        :param handler: what to use to output messages. Defaults to a PrintHandler.
-
-        """
+        """Create an instance."""
         self._level = NOTSET
         self._handler = PrintHandler()
 
@@ -201,3 +208,39 @@ def critical(self, format_string, *args):
 
         """
         self.log(CRITICAL, format_string, *args)
+
+
+class NullLogger:
+    """Provide an empty logger.
+    This can be used in place of a real logger to more efficiently disable logging."""
+
+    def __init__(self):
+        """Dummy implementation."""
+
+    def setLevel(self, value):
+        """Dummy implementation."""
+
+    def getEffectiveLevel(self):
+        """Dummy implementation."""
+        return NOTSET
+
+    def addHandler(self, hldr):
+        """Dummy implementation."""
+
+    def log(self, level, format_string, *args):
+        """Dummy implementation."""
+
+    def debug(self, format_string, *args):
+        """Dummy implementation."""
+
+    def info(self, format_string, *args):
+        """Dummy implementation."""
+
+    def warning(self, format_string, *args):
+        """Dummy implementation."""
+
+    def error(self, format_string, *args):
+        """Dummy implementation."""
+
+    def critical(self, format_string, *args):
+        """Dummy implementation."""

examples/logging_simpletest.py

@@ -2,12 +2,32 @@
 # SPDX-License-Identifier: MIT
 
 # pylint:disable=undefined-variable,wildcard-import,no-name-in-module
-# pylint:disable=no-member
+# pylint:disable=no-member,invalid-name
+
+"""Briefly exercise the logger and null logger."""
 
 import adafruit_logging as logging
 
+# This should produce an error output
+
 logger = logging.getLogger("test")
 
 logger.setLevel(logging.ERROR)
 logger.info("Info message")
 logger.error("Error message")
+
+# This should produce no output
+
+null_logger = logging.getLogger(None)
+
+null_logger.setLevel(logging.ERROR)
+null_logger.info("Info message")
+null_logger.error("Error message")
+
+# This should produce no output
+
+null_logger = logging.getLogger("")
+
+null_logger.setLevel(logging.ERROR)
+null_logger.info("Info message")
+null_logger.error("Error message")