decorators examples

decorators.py

#!/usr/bin/env python

"""
 File: decorators.py
 Description: decorators examples
 Author: Ronald Kaiser <raios dot catodicos at gmail dot com>
"""

import time


# Let's begin with a simple decorator, that adds
# some behaviour to a lazy function


def simple_decorator(fn):
    def wrapper():
        # adding behaviour before execution
        print "before execution"
        fn() 
        # adding behaviour after execution
        print "after execution"
    return wrapper


@simple_decorator
def lazy_function():
    print "zz..."
    time.sleep(2)


# Calling the lazy function to see the result
lazy_function()


# Well, it works! =)
# Now, let's try a decorator for a function with arguments


def another_decorator(fn):
    def wrapper(*args):
        print "well, gonna sleep again"
        fn(*args)
        print "time to wake up!"
    return wrapper


@another_decorator
def another_lazy_function(period, level):
    print "%s..." % ('z'*level)
    time.sleep(period)


# calling another lazy function
another_lazy_function(5, 5)


# Pretty nice, huh?!
# Decorators may receive a list of arguments too.
# Let's try with a function that fires


def load(level):
    def wrap(fn):
        def wrapper():
            for i in range(level):
                print '.'
                time.sleep(0.5)
            fn()
        return wrapper 
    return wrap


@load(5)
def fire():
    print "Bang!"


# let's try to bang!
fire()