The Blog of Nitin J Mutkawoa, AKA @TheTunnelix

In this article, i will get in brief into objects. As usual here are all the articles related to Python:

• Seven steps to compile Python 3.5.0 from source
• Getting started with Python and Anjuta
• Starting up with Python – Part 1 – Numbers and Maths, Variables
• Starting up with Python – Part 2 – Modules and Functions, Strings
• Starting up with Python – Part 3 – Sequences and List, Slicing and Editing
• Starting up with Python – Part 4 – More list functions and Slicing lists
• Starting up with Python – Part 5 – Methods
• Starting up with Python – Part 6 – Sort and Tuples, Strings and stuffs, methods and Dictionary
• Starting up with Python – Part 7 – If statement, Else and elif statements
• Starting up with Python – Part 8 – Nesting and Comparison operators
• Starting up with Python  – Part 9 – And and Or operators
• Starting up with Python – Part 10 – While, For, Infinite and Break Loops
• Starting up with Python – Part 11 – Building functions and Default parameters
• Starting up with Python  – Part 12 – Multiple Parameters, Parameter Types and Tuples as Parameters

30. Object Oriented Program

An object contains data and also has methods. A method in an Object is just like a function and it is called when it is inside an Object and it will use data from the very same object. An example of using a method in an object can be Mauritius.hacks() However, before building objects, classes need to be build. Let’s build a class.

>> class hackersClass:
 ... country="mauritius"
 ... members=8
 ... def thisMethod(self):
 ... return 'This method worked'
 ...
 >>> hackersClass
 <class __main__.hackersClass at 0xb721e32c>

A class has been build and it even shows us that it works. Let’s now make an object. I need the object to get the data from the class. We start by making an object set equal to the class.

>> hackersObject=hackersClass()
 >>> hackersObject.country
 'mauritius'
 >>> hackersObject.members
 8

>> hackersObject.thisMethod()
 'This method worked'

So many objects can be build to refer to the same class. Cool isn’t it?

31. Classes and Self

The keyword class will be needed. This is a like a blueprint which is made to create methods and the “self” is made as we do not now the object name

>> class classname:
... def createName(self,name):
... self.name=name
... def displayName(self):
... return self.name
... def saying(self):
... print "hello %s" % self.name
... 
>>> classname
<class __main__.classname at 0xb722d32c>
>>> first=className()

Lets now use the objects. Now it take self and replace it with the object name.

first=classname()
>>> second=classname()
>>> first.createName('nitin')
>>> second.createName('test')
>>> first.displayName()
'nitin'
>>> first.saying() 

hello nitin

In the last Python post, we have seen Default parameters. In this article, it will be dedicated to Multiple Parameters, Parameter types, and tuples as parameters. Here is a recap from the last article on Python

• Seven steps to compile Python 3.5.0 from source
• Getting started with Python and Anjuta
• Starting up with Python – Part 1 – Numbers and Maths, Variables
• Starting up with Python – Part 2 – Modules and Functions, Strings
• Starting up with Python – Part 3 – Sequences and List, Slicing and Editing
• Starting up with Python – Part 4 – More list functions and Slicing lists
• Starting up with Python – Part 5 – Methods
• Starting up with Python – Part 6 – Sort and Tuples, Strings and stuffs, methods and Dictionary
• Starting up with Python – Part 7 – If statement, Else and elif statements
• Starting up with Python – Part 8 – Nesting and Comparison operators
• Starting up with Python  – Part 9 – And and Or operators
• Starting up with Python – Part 10 – While, For, Infinite and Break Loops
• Starting up with Python – Part 11 – Building functions and Default parameters

27. Multiple Parameters

Now, we will see how to put multiple parameters in functions. A simple example where we want to make a profile for manager’s name having different ages. In the example below, we have the asterisk in front of ages to be able to define as many age we want.

>> def profile(name, *ages):
 ... print name
 ... print ages
 ...

The first value will be treated as a name and everything else after it will be considered as ages. Now, we can call the profile function.

>> profile ('toto', 20,30,40)
 toto
 (20, 30, 40)

The parameter ‘toto’ is treated as a name and other as ages.

28. Parameter types

Now, will we see how to use parameters to convert it into a dictionary? Let’s create a function. Imagine we have a hackers group in Mauritius and we will need to categorized how many are there in the south, center, east, west and north. The idea is to use a double asterisk in from of Mauritius.

>> def hackers(**mauritius):
 ... print mauritius
 ...

>> hackers(south=1,center=3,east=1,west=0,north=0)
 {'west': 0, 'east': 1, 'north': 0, 'center': 3, 'south': 1}

This is how we get a dictionary instead of a tuple. Let’s now combine both to use a dictionary inside a parameter.

> def hackers(country,nickname,*age,**projects):
 ... print country, nickname
 ... print age
 ... print projects
 ...
 >>> hackers('mauritius', 'TheTunnelix', 29,30, tarsnap=2, kernel=1)
 mauritius TheTunnelix
 (29, 30)
 {'kernel': 1, 'tarsnap': 2}

29.Tuples as Parameters

Now, we will gather information from a dictionary and tuples and use that information as parameters. Instead of creating dictionaries, we can use pre-existing ones as parameters. Let’s look at the code below

>> def country(a,b,c):
... return a+b+c

Consider, I already have a tuple as indicated below and we can place the tuple inside the parameter.

>> sum=(4,2,7)
>>> country(*sum)
13

As you can see it output the sum of it. The first star in front sum means that I am working with a tuple and 2 stars means working with a dictionary. In the example below, it gives an example of using the 2 stars.

>> def test(**hello):
... print hello
... 
>>> hackers={'mauritius':5,'india':2,'usa':10}
>>> test(**hackers)
{'mauritius': 5, 'india': 2, 'usa': 10}

This is useful when gathering data from an outside source.

We have now reached yet another interesting part of the Python tutorial on building your own functions and default parameters.

• Seven steps to compile Python 3.5.0 from source
• Getting started with Python and Anjuta
• Starting up with Python – Part 1 – Numbers and Maths, Variables
• Starting up with Python – Part 2 – Modules and Functions, Strings
• Starting up with Python – Part 3 – Sequences and List, Slicing and Editing
• Starting up with Python – Part 4 – More list functions and Slicing lists
• Starting up with Python – Part 5 – Methods
• Starting up with Python – Part 6 – Sort and Tuples, Strings and stuff, methods and Dictionary
• Starting up with Python – Part 7 – If statement, Else and elif statements
• Starting up with Python – Part 8 – Nesting and Comparison operators
• Starting up with Python  – Part 9 – And and Or operators
• Starting up with Python – Part 10 – While, For, Infinite and Break Loops

25. Building functions

We have been using several built-in functions in Python. This time we are going to build our own functions. We will start by defining the function – see line1. After having defined the function, we will need to tell the function what to do. Here is an example where a function is created and instructed what to do.

>> def hackers(x):
... return 'whats up mauritius' + x

Now, the function is used just by inserting the following line. As you can see it returns friends by using the function hackers.

>> print hackers(' friends')
whats up mauritius friends

Another example where a function can be created is by adding a specific number.

>> def addition(z):
... return z+10
... 
>>> print addition(10)
20

26. Default Parameters

Default parameter in the functions is used instead of having a default value. Here is an example of a simple basic function which takes two parameters.

>> def continent(east,west):
... print '%s %s' % (east, west)
... 
>>> continent('australia', 'africa')
australia africa

Now, the function has rewritten a function that already has default values in it. Here is an example. We also noticed that the continent function gave the value Australia and Africa directly.

>> def continent(east='australia', west='africa'):
... print '%s %s' % (east, west)
... 
>>> continent()
australia africa

But what if we want to overwrite Africa and use Madagascar instead? Here is the catch. Whenever a specific value is given, it will overwrite the default value otherwise use the default values

>> continent('australia','madagascar')
australia madagascar
>>> continent()
australia africa 

You can also overwrite default values as such:

>> continent(west='usa')
australia usa