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")decorators in python
'pass function which we want to decorate in decorator callable object'
def our_decorator(func): # func is function to be decorated by decorator
def wrapper(x): # x is parameter which is passed in func
if x%2==0:
return func(x)
else:
raise Exception("number should be even")
return wrapper
@ our_decorator
def func(x): # actual function
print(x,"is even")
func(2)
func(1)
' if you do not want to use @'
func=our_decorator(func)
func(2)python decorator
import functools
# A decorator is a Higher order function "_with_logging"
# It takes the function to be decorated as its argument
# In order to pass in some arbitrary arguments, it must be wrapped into
# another HOF (Higher order function) that will receive the inputs
def with_logging(level=logging.DEBUG, msg = None):
def _with_logging(fn):
# 'wraps' is a HOF that will give fn's name and docs to decorated_fn i.e.
# decorated_fn.__name__ = fn.__name__
# help(decorated_fn) = help(fn)
@functools.wraps(fn)
def decorated_fn(*args, **kwargs):
res = fn(*args, **kwargs)
print("n***************", f"n{msg}", "nExecuting with Args: ", *args, **kwargs)
logging.log(level, res)
return res
return decorated_fn
return _with_logging
# Used this way
@with_logging(level=logging.DEBUG, msg="Some awesome comment")
def hello_world(name):
return f'Hello World {name}'
# Results after calling hello_world("John")
#
# ***************
# Some awesome comment
# Executing with Args: John
# Hello World Johnexamples 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 stringCopyright © 2021 Codeinu
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