Chapter 6: Problem 28

If you are writing a function that accepts an argument and you want to make sure the function cannot change the value of the argument, what should you do?

Short Answer

Expert verified

Answer: You can ensure that a function doesn't change the value of the argument by either passing a copy of the argument to the function or using immutable data structures. Passing a copy ensures any changes made within the function only affect the copy, while using immutable data structures like tuples that can't be modified after creation.

Step by step solution

Understand the concept of immutability

Immutable objects are objects whose state cannot be changed after they are created. When a function accepts an argument, it can sometimes modify the value of that argument. To ensure that the function doesn't change the value of the argument, we should make the object immutable or pass a copy of the argument to the function.

Pass a copy of the argument to the function

If you want to ensure your function cannot alter the value of the argument, pass a copy of the argument to the function rather than passing the original object itself. This way, any changes made to the argument will only affect its copy, and the original remains unchanged. You can create a copy of a list using the `[:]` slicing syntax or use the `copy()` method available for some objects.

Example of passing a copy of an argument

Here's an example showcasing how to pass a copy of the list argument to a function: ```python def modify_list(list_arg): list_arg.append(100) original_list = [1, 2, 3] copy_list = original_list[:] modify_list(copy_list) print("Original list:", original_list) print("Copy list:", copy_list) ``` Output: ``` Original list: [1, 2, 3] Copy list: [1, 2, 3, 100] ```

Use immutable data structures

Make use of immutable data structures in your function, such as tuples, instead of mutable data structures like lists. An immutable data structure cannot be changed after creation, preventing any changes within the function from affecting the original data.

Example of using an immutable data structure

Here's an example showcasing an immutable tuple being used as an argument instead of a mutable list: ```python def modify_tuple(tuple_arg): # This will raise a TypeError since tuples are immutable try: tuple_arg += (100,) except TypeError as e: print("Error:", e) original_tuple = (1, 2, 3) modify_tuple(original_tuple) print("Original tuple:", original_tuple) ``` Output: ``` Error: 'tuple' object does not support item assignment Original tuple: (1, 2, 3) ```

Unlock Step-by-Step Solutions & Ace Your Exams!

Full Textbook Solutions
Get detailed explanations and key concepts
Unlimited Al creation
Al flashcards, explanations, exams and more...
Ads-free access
To over 500 millions flashcards
Money-back guarantee
We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

Recommended explanations on Computer Science Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

If you are writing a function that accepts an argument and you want to make sure the function cannot change the value of the argument, what should you do?

Short Answer

Step by step solution

Understand the concept of immutability

Pass a copy of the argument to the function

Example of passing a copy of an argument

Use immutable data structures

Example of using an immutable data structure

One App. One Place for Learning.

Most popular questions from this chapter

Recommended explanations on Computer Science Textbooks

Game Design in Computer Science

Computer Organisation and Architecture

Computer Programming

Computer Systems

Theory of Computation

Issues in Computer Science

Study anywhere. Anytime. Across all devices.