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MUTABLE AND IMMUTABLE OBJECTS IN PYTHON AND THEIR MEMORY MANAGEMENT

Everything in Python is an object. There are two types of objects in Python



  • Mutable
  • Immutable
Mutable objects are those whose value can be changed after their creation. An example of it is a list.



Immutable objects are those whose value cannot be changed after their creation. A well-known example of this is a tuple.

Mutable objects: lists, sets, dictionaries

Immutable objects: Tuples, integers, floats, strings, frozen sets

Before going deep into this topic, we should know about the id() function in Python.

id() function in python:

This function returns the identity of an object. This is guaranteed to be unique and constant for an object. The id of an object is created when the object is created. See below for examples.

example1:                                                                        

l=[1,2,3]

print(id(l))

Output:

2018064114312

example 2:

x= 10

print(id(x))

Output:

140736328131504


Ok, now let us see some examples of the functionality of mutable and immutable objects.

let us take an example of a list.

l=[1,2,3]

print(id(l))

l.append(5)

print(id(l))

Output:

2018059045576

2018059045576

Here, we can observe that as lists are mutable objects. We can change the value of lists without changing their id.

Now, if we take an example of a tuple, there is no chance of changing their value since it is an immutable object. If we take the example of int, string, which are also immutable, we can change the value of them, but changing their value creates a different id. See the below example.

example1:

x=10

print(id(x))

x=x+10

print(id(x))

Output:

140736328131504

140736328131824

example2:

s="string"

print(id(s))

s=s+"s"

print(id(s))

2018054115200

2018063371320

More on immutable objects:

We cannot change a tuple. But, if a tuple has an immutable object in it, we can change that immutable one in the tuple.

example:

t=(1, 2, [12,3])

t2.append(4)

print(t2)

Output:

(1, 2, [12,3,4])


FOR, VISUALISATION OF THIS CODE IN PYTHON IDLE SEE MY YOUTUBE VIDEO ABOUT THIS: https://youtu.be/tYq5ROASMvs 


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