Python Decorators

Decorators

A decorator is also a function, it takes another function as a parameter and adds some kinds of functionalities and returns function. We have a python function than why we use the decorator function. The decorator function is mainly used to control the functions and reduce the code (Reusable code). To get a better idea see the below

Example1:

'''
  Created on 23-Feb-2018
  
  @author: sairam
  '''
  import time
  def outerFunction(originalFunction):
      def innerFunction(*args, **kwargs):
          start = time.time()
          result = originalFunction(*args, **kwargs)
          print(f'execution time of {originalFunction.__name__} is {time.time()-start}')
          return result
      return innerFunction
  
  # a = outerFunction("hi")
  # a()
  
  @outerFunction
  def addition(a,b):
      return a+b
  
  @outerFunction   
  def subtraction(a,b):
      return a-b
  
  print(addition(1, 3))
  print(subtraction(2, 4))

Output:

execution time of addition is 0.0
4
execution time of subtraction is 0.0
-2

Example2:

'''
  Created on 16-Feb-2018
  
  @author: sairam
  '''
  
  import time
  
  def outerFuncion(originalFunction):
      def innerFunction(*args, **kwargs):
          statTime = time.time()
          originalFunction(*args, **kwargs)
          exectionTime = time.time() - statTime
          print(f"function name is {originalFunction.__name__} and exectionTime is {exectionTime}")
      return innerFunction
  
  #=================================================================================
  @outerFuncion
  def sum():
      result = 0
      for r in range(0,10000):
          result+=r
      return result
  
  
  sum()
  #=================================================================================
  @outerFuncion
  def multiplication(num):
      result = 0
      for r in range(0,10000):
          result*=num
      return result
  
  multiplication(10)
  
  #=================================================================================
  @outerFuncion
  def division(num):
      result = 0
      for r in range(0,10000):
          result/=num
      return result
  
  division(10)

Output:

function name is sum and exectionTime is 0.0029959678649902344
function name is multiplication and exectionTime is 0.001999378204345703
function name is division and exectionTime is 0.0019998550415039062

The use of Decorators:

Analytics, logging, and instrumentation

Validation and runtime checks

Creating frameworks

This avoids boiler-plate code.

Python Decorators,RegularPython