Python Scripting for Network Engineers: Realizing Network Automation for Reliable Networks by Hassan Wajid

Author:Hassan, Wajid [Hassan, Wajid]
Language: eng
Format: epub
Publisher: UNKNOWN
Published: 2019-05-27T16:00:00+00:00

Chapter 6 Functions in Python Scripting

6.1 Objectives

The main objectives of this chapter are to discuss:

• Functions, Constructs and its Uses

• Built-in and User Defined Functions

• Discusses Object Oriented Programming

• Discusses Classes and its usage

6.2 Introduction

Python is a general-purpose high-level programming language. Like any other programming language, Python has some codes that are used more than once and hence need not to be rewritten over and over. This chapter discusses how the Python script can be modularized and made repeatable. These repeatable codes are called Functions.

Functions, Object Oriented Programming and Classes are discussed in this chapter that are used extensively in Python Scripts for writing large scripts which can handle many input requests, interrupts and generate kind of actions with changing conditions of the inputs and requirements.

The main objectives of this chapter include; being able to understand why and how programmers divide programs up into sets of cooperating functions, to be able to define new functions in Python and lastly to understand the details of function calls and parameter passing in Python.

6.2.1 Functions

Python has some pieces for code that have been organized into a block and can be reused more than once for a single related function. These blocks of codes are the ones referred to as functions of Python. They provide high-levels of reusing program codes and hence enhancing modularity in the program development process. Creating a customized function is easy in Python.

Code for creating a function

Figure 6-1 Code demonstration of creating a function

Figure 6-2 output in python

Functions in Python begin with the key-word def which is then followed by the name of the function and parenthesis. The parenthesis takes all the input parameters and the code block in every function begins with a colon. The return statement is used to exit any function and can be called in any other part of the program.

6.2.2 Object-oriented programming

Python is known to be a language. This is because almost everything is in Python is written in terms of objects which are associated with properties and methods.

6.2.3 Classes

Classes in Python are like object constructors and is created with the keyword class. Code for creating a class in python

Figure 6-3 Code demonstration of creating a function

Figure 6-4 Code output in python

Figure 6-5 Code representing how to create a class in Python

The use of functions and objects in Python programming makes it easy to design a functional code with full functionalities and be easily understandable (Ozer, 2017). Functions increase modularity in program codes and hence make them easy to be reused. This chapter mainly focuses on the programming using Python functions and classes that makes Python termed as an object-oriented programming language.

6.3 Program Components in Python

Python language has several components. These components include; numbers, strings, sets, lists, dictionaries, tuples and functions (Rivers & Koedinger, 2017). All these components work together in meeting the specifications of a given program code. Python combines its components in one program hence ensuring that a fully functional program which meets the needs of the users is designed in the process.

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