Skip to main content

Python Decorator

🐍 When you need to use a function and add more code to it while retaining original function, you can use decorator.
A decorator is nothing but a function to which another function is passed, and both are run.
First we will look at Closure in Python. It is calling of a function inside another function from outside. Example of a Closure:


def one(func):



  def two(*args):



    print(f"You are running function {two.__name__} and have passed arguments as follows: {args}")



    print(f"Result of the two numbers {args[0]} and {args[1]} is {func(*args)}")



  return two



def addfunc(x,y):



  print("Addition")



  return x+y



def subfunc(x,y):



  print("Subtraction")



  return x-y






addouter = one(addfunc)



subouter = one(subfunc)



addouter(4,3)



subouter(4,3)

Output

You are running function two and have passed arguments as follows: (4, 3)
Addition
Result of the two numbers 4 and 3 is 7
You are running function two and have passed arguments as follows: (4, 3)
Subtraction
Result of the two numbers 4 and 3 is 1
  1. Created function "one" with another function inside it named "two"
  2. Function "one" returns function "two"
  3. Function "two" calls the function passed to function "one"
  4. We created two more functions named "addfunc" and "subfunc". These functions adds two numbers passed to it and subtracts two numbers passed to it respectively.
  5. We passed these functions to function "one"
Now let's try the same thing using decorator


def one(func):



  def two(*args):



    print(f"You are running function {two.__name__} and have passed arguments as follows: {args}")



    print(f"Result of the two numbers {args[0]} and {args[1]} is {func(*args)}")



  return two



@one



def addfunc(x,y):



  print("Addition")



  return x+y







@one



def subfunc(x,y):



  print("Subtraction")



  return x-y







addfunc(4, 3)



subfunc(4, 3)

Output


You are running function two and have passed arguments as follows: (4, 3)
Addition
Result of the two numbers 4 and 3 is 7
You are running function two and have passed arguments as follows: (4, 3)
Subtraction
Result of the two numbers 4 and 3 is 1
Now we need not save returned function to call them. It can will be directly called and functions addfunc and subfunc will be passed as we used decorator

Comments

Post a Comment

Popular posts from this blog

Python - List - Append, Count, Extend, Index, Insert, Pop, Remove, Reverse, Sort

🐍 Advance List List is widely used and it's functionalities are heavily useful. Append Adds one element at the end of the list. Syntax list1.append(value) Input l1 = [1, 2, 3] l1.append(4) l1 Output [1, 2, 3, 4] append can be used to add any datatype in a list. It can even add list inside list. Caution: Append does not return anything. It just appends the list. Count .count(value) counts the number of occurrences of an element in the list. Syntax list1.count(value) Input l1 = [1, 2, 3, 4, 3] l1.count(3) Output 2 It returns 0 if the value is not found in the list. Extend .count(value) counts the number of occurrences of an element in the list. Syntax list1.extend(list) Input l1 = [1, 2, 3] l1.extend([4, 5]) Output [1, 2, 3, 4, 5] If we use append, entire list will be added to the first list like one element. Extend, i nstead of considering a list as one element, it joins the two lists one after other. Append works in the following way. Input l1 = [1, 2, 3] l1.append([4, 5]) Output...
Post a Comment
Read more

Difference between .exec() and .execPopulate() in Mongoose?

Here I answer what is the difference between .exec() and .execPopulate() in Mongoose? .exec() is used with a query while .execPopulate() is used with a document Syntax for .exec() is as follows: Model.query() . populate ( 'field' ) . exec () // returns promise . then ( function ( document ) { console . log ( document ); }); Syntax for .execPopulate() is as follows: fetchedDocument . populate ( 'field' ) . execPopulate () // returns promise . then ( function ( document ) { console . log ( document ); }); When working with individual document use .execPopulate(), for model query use .exec(). Both returns a promise. One can do without .exec() or .execPopulate() but then has to pass a callback in populate.
1 comment
Read more

683 K Empty Slots

  Approach #1: Insert Into Sorted Structure [Accepted] Intuition Let's add flowers in the order they bloom. When each flower blooms, we check it's neighbors to see if they can satisfy the condition with the current flower. Algorithm We'll maintain  active , a sorted data structure containing every flower that has currently bloomed. When we add a flower to  active , we should check it's lower and higher neighbors. If some neighbor satisfies the condition, we know the condition occurred first on this day. Complexity Analysis Time Complexity (Java):  O(N \log N) O ( N lo g N ) , where  N N  is the length of  flowers . Every insertion and search is  O(\log N) O ( lo g N ) . Time Complexity (Python):  O(N^2) O ( N 2 ) . As above, except  list.insert  is  O(N) O ( N ) . Space Complexity:  O(N) O ( N ) , the size of  active . Approach #2: Min Queue [Accepted] Intuition For each contiguous block ("window") of  k  po...
Post a Comment
Read more