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Description:

pythondevlog 1.2

devlog
No more logging in your code business logic with python decorators.
Logging is a very powerful tool for debugging and monitoring your code. But if you are often ommitting logging
statements, you will quickly find yourself overcrowded with logging statements.
Fortunately, you could avoid this by using the python decorator. This library provide easy logging for your code without
stealing readability and maintainability. Furthermore, it also provides stack trace to get full local variable on the
function.
How to use:
To use this library, you just need to add the decorator to your function. Depending on when you want to log, you can use
the decorator as below:
import logging

from devlog import log_on_start, log_on_end, log_on_error

logging.basicConfig(level=logging.DEBUG)

@log_on_start
@log_on_end
def test_1(a, b):
return a + b

@log_on_error
def test_2(a, b):
return a / b

if __name__ == '__main__':
test_1(1, b=2)
# INFO:__main__:Start func test_1 with args (1,), kwargs {'b': 2}
# INFO:__main__:Successfully run func test_1 with args (1,), kwargs {'b': 2}

test_2("abc", "def")
# ERROR:__main__:Error in func test_2 with args ('abc', 'def'), kwargs {}
# unsupported operand type(s) for /: 'str' and 'str'.

What devlog can do for you
Decorators
devlog provides three different decorators:

LogOnStart: Log when the function is called.
LogOnEnd: Log when the function is finished.
LogOnError: Log when the function is finished with error.

Use variables in messages
The message given to decorators are treated as a format string which takes the function arguments as the format
arguments.
The following example shows how to use variables in messages:
import logging

from devlog import log_on_start

logging.basicConfig(level=logging.DEBUG)

@log_on_start(logging.INFO, 'Start func {callable.__name__} with args {args}, kwargs {kwargs}')
def hello(name):
print("Hello, {}".format(name))

if __name__ == "__main__":
hello("World")

Which will print:
INFO:__main__:Start func hello with args ('World',), kwargs {}
Documentation
format variables
The following variables are available in the format string:

Default variable name
Description
LogOnStart
LogOnEnd
LogOnError

callable
The function object
Yes
Yes
Yes

args/kwargs
The arguments, key arguments passed to the function
Yes
Yes
Yes

result
The return value of the function
No
Yes
No

error
The error object if the function is finished with error
No
No
Yes

base arguments
Available arguments in all decorators are:

Arguments
Description

logger
The logger object. If no logger is given, the devlog will create a logger object with the name of the module where the function is defined. Default is logging.getLogger(callable.__name__)

handler
A custom log handler object. Only available if no logger object is given,

args_kwargs
Set true if the message format using args, kwargs format or false to use function parameter name format. Default True

callable_format_variable
The format variable to use for callable. Default is callable

trace_stack
Set to True if you want to get the full stack trace. Default is False or capture_local

capture_locals
Set to True if you want to get the local variable of the function. Default is False (or trace_stack on log_on_error decorator)

include_decorator
Set to True if you want to include the devlog libray on the stack. Default is False

log_on_start

Arguments
Description

level
The level of the log message. Default is logging.INFO

message
The message to log. Could using {args} {kwargs} or function parameter name but not both. Default is Start func {callable.__name__} with args {args}, kwargs {kwargs}

log_on_end

Arguments
Description

level
The level of the log message. Default is logging.INFO

message
The message to log. Could using {args} {kwargs} or function parameter name but not both. Default is Successfully run func {callable.__name__} with args {args}, kwargs {kwargs}

result_format_variable
The format variable to use for reference the return from callable. Default is result

log_on_error

Arguments
Description

level
The level of the log message. Default is logging.ERROR

message
The message to log. Could using {args} {kwargs} or function parameter name but not both. Default is Successfully run func {callable.__name__} with args {args}, kwargs {kwargs}

on_exceptions
A tuple containing exception classes or a single exception, which should get caught and trigger the logging. Default is tuple() (All exception will get caught)

reraise
Control whether the exception should be reraised after logging. Default is True

exception_format_variable
The format variable to use for reference the exception raised in callable. Default is error

Extras
Stack trace
The stack trace configuration.

method
Description

set_stack_start_frames
The number of frames to skip at the start (positive value). Default is 0

set_stack_removal_frames
The number of frames to remove from the back of the stack trace (positive value). Default is 6 (the last 6 frame usually from the devlog module)

Custom exception hook
Override the default exception hook with a custom function.
import devlog

devlog.system_excepthook_overwrite() # Overwrite the default exception hook

This will replace the sys.excepthook with the devlog.excepthook.

Arguments
Description

out_file
The path to the file to write the log. Default is crash.log