Why are Python strings immutable? Best practices for using them

Question

I want to know the reason behind the immutable nature of string in Python and how can I program without mutable strings?

Answer 1

When you are having string format data, you'll be assured that it stays the same. Assume that you have created one function named Foo in Python as below with a string argument, and would then modify the string; then the Foo's name would suddenly change:

class Foo(object):

    def __init__(self, name):

        self.name = name

name = "Hello"

foo = Foo(name)

name[0] = "J"

If the strings are mutable, then you have to make copies all the time to prevent errors and confusion. 

It also provides the benefit that a single character is no different from a string of length one, so all string operators apply to characters as well.

Now coming to your concern, programming with immutable strings, just treat them as you treat numbers: as values, not as objects. If you want to change the first letter of the name would be

name = "J" + name[1:]