Creating sample module for logging (#5)

Author: cosmicboy79

.gitignore

@@ -195,3 +195,6 @@ cython_debug/
 
 # PyCharm
 .idea
+
+# user generated files
+*output.log

src/learning/decorating.py

@@ -0,0 +1,66 @@
+"""
+Decorators receive a function to be executed when it is called.
+However, some other action can be done before or after its execution.
+The idea is to encapsulate some behaviour that should happen on top of
+some operation and can be reused everywhere it is needed.
+"""
+from functools import wraps
+from enum import Enum
+from datetime import datetime
+
+class Level(Enum):
+    NONE = 0
+    INFO = 1
+    DEBUG = 2
+
+LOG_FILE_NAME = "output.log"
+
+# If you’ve called @name without arguments, then the
+# decorated function will be passed in as _func. If you’ve
+# called it with arguments, then _func will be None, and
+# some of the keyword arguments may have been changed from
+# their default values. The asterisk in the argument list means
+# that you can’t call the remaining arguments as positional arguments.
+def logme(_func=None, *, level: Level = Level.NONE):
+    def decorated_function(func):
+        @wraps(func) # this ensures docstring, function name, arguments list, etc. are all copied
+                     # to the wrapped function - instead of being replaced with wrapper's info
+        def wrapper(*args, **kwargs):
+            if show_info():
+                with open(LOG_FILE_NAME, "a+") as log_file:
+                    log_file.writelines("[{}] Executing function: {}\n".format(get_current_timestamp(), func.__name__))
+
+            result = func(*args, **kwargs)
+
+            if show_debug():
+                with open(LOG_FILE_NAME, "a+") as log_file:
+                    log_file.writelines("[{}] Result of function {} is: {}\n".format(get_current_timestamp(), func.__name__, result))
+
+            return result
+
+        def get_current_timestamp():
+            return datetime.now().strftime('%Y%m%d-%H:%M:%S')
+
+        def show_info():
+            if level == Level.NONE:
+                return False
+
+            # DEBUG also shows INFO
+            return level._value_ <= Level.DEBUG._value_
+
+        def show_debug():
+            # INFO does not show DEBUG
+            return level != Level.NONE and level == Level.DEBUG
+
+        return wrapper
+
+    # In this case, you called the decorator with arguments.
+    # Return a decorator function that takes a function as an
+    # argument and returns a wrapper function.
+    if _func is None:
+        return decorated_function
+    # In this case, you called the decorator without arguments.
+    # Apply the decorator to the function immediately.
+    else:
+        return decorated_function(_func)
+

src/learning/logging/__init__.py

@@ -0,0 +1,22 @@
+from logging.mylog import logme, Level
+
+@logme
+def add(a, b):
+    return a + b
+
+@logme(level=Level.INFO)
+def subtract(a, b):
+    return a - b
+
+@logme(level=Level.DEBUG)
+def multiply(a, b):
+    return a * b
+
+@logme
+def divide(a, b):
+    return a / b
+
+print("Adding two numbers: " + str(add(1, 2)))
+print("Subtracting two numbers: " + str(subtract(8, 3)))
+print("Multiplying two numbers: " + str(multiply(5, 6)))
+print("Dividing two numbers: " + str(divide(45, 5)))