What is a class and what are the benefits of using them in programming
A class is an example of a structured data type. It is one form of organizing code in computer programs. It can be defined as a group of related data items (variables) that are organized and treated as if they were a single entity, with behavior specified by the way each member (instance) of the class is accessed and modified. A class can be described as a data type and a set of functions that operate on its instances. The behavior of the variables is what determines the value or behavior of the class by means of applying the functions to its variables. This way, code written for one class may apply to all instances of that class.
The benefits of using a class in programming is that it allows for consistency across code and easier maintenance. By creating a class, one can have multiple functions that work on instances of the class and can be reused in other parts of the program if needed. For example, if one was to write code that works with an object, they could just focus on how to create an object and how to access its properties rather than focus on every function they want to perform with the object.
In general, a class is a tool used to organize code and functions together in a way that they can be maintained easier and or reused.
Last edited by timxu116 on 2 Jul 2014, 15:32, edited 1 time in total.
How to create a class in Python
The class statement in Python must contain two things: the name of the class, and the bodies of one or more functions that define a data structure for storing or aggregating some kind of information. The name given to a Python class can be any valid identifier. It may only contain alphanumeric characters, underscores, and periods. It is suggested to use lowercase letters for class names. For example, if someone want to create a class called line class, the first step is to make a class statement in Python, like import this_class class this_class.
All of the functions that define a class must be defined inside of a class statement. If a function is not defined inside of the class statement, then it is a simple function, which does not belong to any class. The body of each Python class can be written as one or more Python functions and classes that define methods. Inside the body may also be attributes: variables that relate to an object or elements of an object. For example, if someone want to create a class called line class which has two attributes, length and calliper, the first step is to define a line class in Python like this:
Examples of classes in use
Classes can be used to create classes that have multiple levels of inheritance, so it is easy to create a class hierarchy in Python. For example, if someone want to create a class called “Car class”, it is possible to also have another class called “Car subclass”. It is also possible to have another subclass called CarSubclassSuperclass. In this way, the inheritance relationships are automatically created as more levels are added.2.
class Car(object): def drive(self): # do something with wheels print(“Car driving…”)
In this class, there is an attribute called “drive” that is inherited by the subclass. So when a Car object is created, it inherits this attribute automatically. The object can also override the inherited “drive” method. In this case, it calls a new drive method written by the programmer. All code examples in this article have been written in Python 3.x version.3.
class CarSubclass(Car): def drive(self): print(“Car driving…”) car = CarSubclass() # create a subclass object car.drive() # run the method of the super class
2.1 Inheritance Inheritance is a feature that allows one class to take the attributes (data members) of another class and use them as if they were its own. In Python, an inherited data member can be referred to as self.
The different methods that can be used on classes
There are four ways on how to work with classes in Python. 1. Using class(es) and class inheritance When you create a new class, it is created empty and it can be used to group related data elements within a program (i.e., you can combine more than one variable into one by using the built-in function).2. Using classinstance() function The function called “classinstance” is used to create instances of classes from a given class object (an object representing an existing class).3. Using __init__() function The function is called “__init__” and is used to initialize newly created instances of a class.4. Using __delattr__() function It is the inverse of the __setattr__() function. It works like the del statement to delete an attribute from an instance of a class. It is used to delete an attribute from an instance of a class.5. Using __delattr__() function
def __init__(self, x=0, y=0): self.x = x self.y = y def __delattr__(self, name): del self.name def getX(self): return self.x def setX(self, value): self.x = value class Point2(Point): def __init__(self, x=0, y=0, name=”p”): self.x = x self.y = y self.name = name def getX(self): return self.x def setX(self, value): self.x = value
Class inheritance and how it works
Class can be related to one another by creating a hierarchical structure. It is possible to create a class that inherits from another class in Python (i.e., it can inherit all the attributes and behaviors from the parent class). A child class inherits from its parents along with adding additional behaviors and attributes of its own. For example, if someone wants to create a class called “Car” and also want to create a “CarSubclass”, it is possible to create a child class by inheriting from the parent class. It is possible to create a “CarSuperclass” that can be inherited by both classes, so that the child classes can inherit from more than one parent.
The process is quite simple:
a) Specify the parent class in the child class definition, like this:
An example is given below – Create a new class called “Car” that inherits from the “ChildOfAMan” class.
b) Include the definition of child classes at the end of a class definition. It includes all the attributes and behaviors of parent classes. When a child class is defined, it inherits all of the attributes and behaviors of the parent class.
An example is given below – Create a new class called “CarSubclassOfAMan” that inherits from “Car” and also inherit from another class called “Animal”.
class CarSubclassOfAMan(Car, Animal):