README.md

PythonLogger

Log python scripts using decorators

This repository contains an example of how to trace Python code by using two logging decorators, Logger.trace and Logger.log. Logger.log simple prints a string at the current indent level. Logger.trace prints the name of the function/method along with its arguments and prints the return value upon exit. To trace a function/method you must decorated it with then names of the arguments. In the case of a class method, the first argument is always a reference to the class.

Example

  from logger import Logger
  
    class some_class:
        # decorate the constructor, one string for each argument!
        @Logger.trace('self','x')
        def __init__(self, x):
            self.x = x

        # decorarate a method
        @Logger.trace('self', 'y')
        def add(self, y):
            return self.x + y

    # decorate a function
    @Logger.trace('i')
    def g(i):
        return 3 * i

    @Logger.trace('i', 'j')
    def f(i, j):
        Logger.log("I am about to instantiate some_class {0} time".format(1))
        a_class = some_class(g(i))
        return a_class.add(g(j))

    print("The answer is", f(3,4))

The output indents for each level of function call

Entering f
|   i: 3
|   j: 4
|   I am about to instantiate some_class 1 time
|   Entering g
|   |   i: 3
|   Exiting g -> 9
|   Entering some_class.__init__
|   |   self: <__main__.some_class object at 0x000002CBF9FB8978>
|   |   x: 9
|   Exiting some_class.__init__ -> None
|   Entering g
|   |   i: 4
|   Exiting g -> 12
|   Entering some_class.add
|   |   self: <__main__.some_class object at 0x000002CBF9FB8978>
|   |   y: 12
|   Exiting some_class.add -> 21
Exiting f -> 21
The answer is 21