An example showing off function decorators & class decorators

decorators.py

"""
  @author Victor I. Afolabi
  A.I. Engineer & Software developer
  javafolabi@gmail.com
  
  Created on 05 October, 2017 @ 03:35 PM.
  
  Copyright (c) 2017. Victor. All rights reserved.
"""

print('1. METHOD DECORATORS. [NO ARGUMENTS]')

def meth_decorator(original_func):

    # Inner/wrapper function.
    def wrap():
        print('\nMethod decorator ran before {}()'.format(original_func.__name__))

        # Return the call to the original function.
        return original_func()

    # Return the inner function waiting to be called.
    return wrap


# Method to be wrapped.
print('Method Decorator Syntax 1:')

def display():
    print('Hello, World!')

# Step 1: Wrap the display method.
display = meth_decorator(display)

# Step 2: Call the wrapped display method.
display()

print(70 * '=')

print('Method Decorator Syntax 2:')

@meth_decorator
def display():
    print('Hello, World!')

# Call the wrapped display method.
display()


print(80 * '#', '\n')

################################################################################

print('2. METHOD DECORATORS. [WITH ARGUMENTS]')

def meth_decorator(original_func):

    # Inner/wrapper function (optional argument & keyword arguments).
    def wrap(*args, **kwargs):
        msg = '\nMethod decorator ran before {}({}, {})'\
              .format(original_func.__name__, args, kwargs)
        print(msg)

        # Return the original function passing the args and kwargs.
        return original_func(*args, **kwargs)
    
    # Return the wrapper function waiting to be called.
    return wrap


# Method to be wrapped.

print('Method Decorator Syntax: 1')

# Method without argument.
def display():
    print('Hello, World!')

# Method with argument.
def display_args(name, greet='Hello'):
    print('{}, {}!'.format(name, greet))

# Step 1: Wrap the display method.
display = meth_decorator(display)
display_args = meth_decorator(display_args)

# Step 2: Call the wrapped display method.
display()
display_args('John')
display_args('Jane', greet='Hi')

print(70 * '=')


print('Method Decorator Syntax 2:')

# Method without argument.
@meth_decorator
def display():
    print('Hello, World!')

# Method with argument.
@meth_decorator
def display_args(name, greet='Hello'):
    print('{}, {}!'.format(name, greet))

# Call the wrapped methods.
display()
display_args('John')
display_args('Jane', greet='Hi')


print(80 * '#', '\n')

###############################################################################


print('1. CLASS DECORATORS.')

class decorator(object):

    def __init__(self, original_func):
        self.original_func = original_func

    def __call__(self, *args, **kwargs):
        msg = '\nClass decorator ran before {}({}, {})'\
              .format(self.original_func.__name__, args, kwargs)
        print(msg)

        return self.original_func(*args, **kwargs)


@decorator
def display():
    print('Hello, World!')

@decorator
def display_args(name, greet='Hello'):
    print('{}, {}!'.format(name, greet))

display()
display_args('Jimmy')
display_args('Doe', "What's poppin'")