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Null Logger #18

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Merged
merged 3 commits into from
Mar 17, 2021
Merged

Null Logger #18

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ea05e92
Add a NullLogger class for efficient disabling of logging
dastels Mar 4, 2021
377a5d8
Pylint tweaks for the global manipulation
dastels Mar 4, 2021
055a8c0
Make pylint happy
dastels Mar 4, 2021
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57 changes: 50 additions & 7 deletions adafruit_logging.py
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Original file line number Diff line number Diff line change
Expand Up @@ -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()

Expand Down Expand Up @@ -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."""
22 changes: 21 additions & 1 deletion examples/logging_simpletest.py
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Original file line number Diff line number Diff line change
Expand Up @@ -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")