Book Image

Learning Python

By : Romano
Book Image

Learning Python

By: Romano

Overview of this book

Learning Python has a dynamic and varied nature. It reads easily and lays a good foundation for those who are interested in digging deeper. It has a practical and example-oriented approach through which both the introductory and the advanced topics are explained. Starting with the fundamentals of programming and Python, it ends by exploring very different topics, like GUIs, web apps and data science. The book takes you all the way to creating a fully fledged application. The book begins by exploring the essentials of programming, data structures and teaches you how to manipulate them. It then moves on to controlling the flow of a program and writing reusable and error proof code. You will then explore different programming paradigms that will allow you to find the best approach to any situation, and also learn how to perform performance optimization as well as effective debugging. Throughout, the book steers you through the various types of applications, and it concludes with a complete mini website built upon all the concepts that you learned.
Table of Contents (14 chapters)
13
Index

Input parameters

At the beginning of this chapter, we saw that a function can take input parameters. Before we delve into all possible type of parameters, let's make sure you have a clear understanding of what passing a parameter to a function means. There are three key points to keep in mind:

  • Argument passing is nothing more than assigning an object to a local variable name
  • Assigning an object to an argument name inside a function doesn't affect the caller
  • Changing a mutable object argument in a function affects the caller

Let's look at an example for each of these points.

Argument passing

Take a look at the following code. We declare a name x in the global scope, then we declare a function func(y) and we call it, passing x. I highlighted the call in the code.

key.points.argument.passing.py

x = 3
def func(y):
    print(y)
func(x)  # prints: 3

When func is called with x, what happens is that within its local scope, a name y is created, and it's pointed to the same object x...