Python Closures

(1) What Is A Closure Method In Python?

As the name suggests, the method which is inside another method is called the closure method.
Because it is closed inside the parent method, hence the name closure method.
What the extra Python is providing here is that you can return the closure method from the parent method.
An important thing is that the closure method will be able to remember the parent class variables, which are non-local to the closure methods.

(2) How To Use Closure Method In Python?

Let us understand this by using an example.

Example:

def parent():
    x = 10
    y = 20
    
    def add():
        print('Addition:', x + y)
        
    return add

obj = parent()

obj()

Output:

Addition: 30

Note:

Here the add( ) method is the closure method because it is inside the parent( ) method.
The first point about the closure method is that we can return it from the parent method, which we have done in ‘return add’.
Here ‘obj’ variable is storing the closure method ‘add’.
We can use the ‘obj’, like a function to access the add( ) method.
The second thing about the closure method is that it will be able to remember the parent class variables, here it is ‘x’ and ‘y’.
Hence it is printing 10 +20 = 30.

(3) Where To Use Closure Method In Python?

When there are few methods (one method in most cases) to be implemented in a class, closures can provide an alternate and more elegant solution.
But when the number of attributes and methods gets larger, it’s better to implement a class.
Closures can avoid the use of global values and provides some form of data hiding.
It can also provide an object–oriented solution to the problem.

Example:

def Student(name,rollno,subject,mark):
    def details():
        print('Student Name:',name)
        print('Student Roll No:',rollno)
        print('Student Subject:',subject)
        print('Student Mark:',mark)
    return details

obj = Student('Abhispa',999,'Math',98)

obj()

obj = Student('Abhispa',999,'Math',98)

obj()

Note:

Here Student method is having the ‘details’ closure method, which is returned from the ‘Student’ method.
You can use the ‘obj’ to call the ‘details’ method.

(4) Example Of Closure Method In Python?

Example:

def operations(x,y,operation):
    
    def addition():
        print('Addition:',x + y)
        
    def substraction():
        print('Substraction:',x-y)
    
    def multiplication():
        print('Multiplication:',x*y)
    
    def division():
        print('Division:',x/y)
    
    if operation == 'add':
        return addition
    if operation == 'substract':
        return substraction
    if operation == 'multiply':
        return multiplication
    if operation == 'divide':
        return division

operation1 = operations(3,4,'add')
operation2 = operations(3,4,'substract')
operation3 = operations(3,4,'multiply')
operation4 = operations(3,4,'divide')

operation1()
operation2()
operation3()
operation4()

Output:
Addition: 7
Substraction: -1
Multiplication: 12
Division: 0.75

Note:

Here ‘operation()’ is the parent method and the method insides are the closure methods.
You can call these closure methods to do specific operations.

Praudyog

Python Closures

Python Closures

Table Of Contents:

(1) What Is A Closure Method In Python?

(2) How To Use Closure Method In Python?

Example:

(3) Where To Use Closure Method In Python?

Example:

(4) Example Of Closure Method In Python?

Example:

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