Decorators in python

Decorator python

def our_decorator(func):
    def function_wrapper(x):
        print("Before calling " + func.__name__)
        func(x)
        print("After calling " + func.__name__)
    return function_wrapper

@our_decorator
def foo(x):
    print("Hi, foo has been called with " + str(x))

foo("Hi")

Source: python-course.eu

Decorators in python

def deco(function):
    def wrap(num):
        if num % 2 == 0:
            print(num,"is even ")
        else:
            print(num,"is odd")
        function(num)
    return wrap
    
@deco
def display(num):
    return num
display(9)   # pass any number to check whether number is even or odd

Examples of function decorators in Python

from functools import wraps

def logit(func):
    @wraps(func)
    def with_logging(*args, **kwargs):
        print(func.__name__ + " was called")
        return func(*args, **kwargs)
    return with_logging

@logit
def addition_func(x):
   """Do some math."""
   return x + x


result = addition_func(4)
# Output: addition_func was called

Source: book.pythontips.com

Decorators in python

# this functon converts any string into uppercase
def deco(function):
    def wrap(s):
        return s.upper()
        function(s)
    return wrap

@deco
def display(s):
    return s 
print(display("not bad"))

Python decorator

from functools import wraps
def debug(func):
    @wraps(func)
    def out(*args, **kwargs):
        print('hello world')
        return func(*args, **kwargs)
    return out

@debug
def add(x, y):
    return x + y

Examples of function decorators in Python

from functools import wraps

def logit(logfile='out.log'):
    def logging_decorator(func):
        @wraps(func)
        def wrapped_function(*args, **kwargs):
            log_string = func.__name__ + " was called"
            print(log_string)
            # Open the logfile and append
            with open(logfile, 'a') as opened_file:
                # Now we log to the specified logfile
                opened_file.write(log_string + '\n')
            return func(*args, **kwargs)
        return wrapped_function
    return logging_decorator

@logit()
def myfunc1():
    pass

myfunc1()
# Output: myfunc1 was called
# A file called out.log now exists, with the above string

@logit(logfile='func2.log')
def myfunc2():
    pass

myfunc2()
# Output: myfunc2 was called
# A file called func2.log now exists, with the above string

Source: book.pythontips.com

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