Classes in Python
Classes in Python are a fundamental part of object-oriented programming. They serve as blueprints for creating objects, allowing for the encapsulation of data and functionality. By defining attributes and methods within a class, developers can create reusable and organized code. In Python, classes enable the implementation of inheritance, polymorphism, and encapsulation, facilitating the creation of complex and modular software systems.
5 Key excerpts on "Classes in Python"
- Chaowei Yang(Author)
- 2017(Publication Date)
- CRC Press(Publisher)
...Section II Python Programming 3 Introduction to Python Learning a programming language is a practical and progressive journey. You will begin with the basics, and gradually increase your skills at complex coding. This chapter will introduce fundamental Python components, including classes and objects, syntax, data types, operators, functions, flow control, exceptions, input/output, and modules. A number of libraries are available for specific development, including graphical user interfaces, databases, Internet, and web programming. To facilitate the learning process, you will utilize your understanding of GIS to start building a mini-GIS package while learning the programming language. 3.1 Object-Oriented Support One of Python’s most important characteristics is object-oriented structure. Foundational Python programming requires understanding concepts about classes and objects, inheritance, composition, package, and class sharing. Python provides the mechanism to define a class and create objects from that class. Classes and objects are widely used in Python. Objects are instances of classes. Objects have attributes and methods. Dot(.) refers to attributes and methods of an object. In Chapter 2, this book defined Point class and created p1 as a point object. You can use p1.x and p1.calDis () to call the attribute and method of the object. Inheritance helps you reuse the attributes and methods of a class (superclass) by using the super class to define new classes in the format ‘class subclass (superclass)’. All public and protected attributes and methods are inherited by subclasses automatically. Private attributes and methods will not be inherited. For example, three vector classes (Point, Polyline, and Polygon) are defined by inheriting the Feature class’s method draw () as detailed in Chapter 2. Composition helps maintain the part–whole relationship, where one object of a class includes objects of other classes...
eBook - ePubBioinformatics Algorithms
Design and Implementation in Python
- Miguel Rocha, Pedro G. Ferreira(Authors)
- 2018(Publication Date)
- Academic Press(Publisher)
...When, on the other hand, the module is imported by some other program, the execution of the module's code is prevented. This feature is particularly useful for testing purposes. With the elements presented in this section, you should be able to start tackling your programming challenges and write our own Python programs. To provide an example, let us check a simple program that reads a string, representing a DNA sequence, and computes the frequency of each nucleotide, also checking if there are non-valid characters. Notice that the whole code can be put in a single file, or in alternative, the two functions can be part of a module (let's say called sequences. py) and in this case, the main program would start with the line: 2.5 Object-Oriented Programming 2.5.1 Defining Classes and Creating Objects Object-oriented programming (OOP) is a popular paradigm that is based in the concepts of objects, classes and inheritance. This paradigm provides increased modularity, allowing the developed code to be encapsulated and more easily reused. Python supports OOP, allowing the definition of new classes by the programmer. Also, it provides a number of pre-defined classes, some of which were already presented in previous sections, including lists and dictionaries. Classes are central concepts in OOP, representing an entity to be modeled. Classes allow to model objects that represent entities within the programs. They can be used to model entities such as strings, biological sequences, or more complex entities such as databases or networks. Classes enclose two major components: one that specifies the data contents to be handled and a second component that specifies the behavior, i.e. the functionality that allows manipulating the respective contents...
eBook - ePub- Joy Ko, Kyle Steinfeld(Authors)
- 2018(Publication Date)
- Routledge(Publisher)
...This portability is related to another advantage to the formal approach: that explicitness breeds clarity. The formality of object-oriented design requires us to think carefully and concretely about our intentions and the details of their realization. Operating in a medium that insists on lucid expression can be a catalyst in any creative process. With these advantages clarified, and in support of true OOP, let us now proceed to consolidating what we have learned about the construct that most embodies it: the class. THE ANATOMY OF A CLASS Since our first mention of classes in Chapter 1.02, we have fleshed out quite a bit more of this important construct. In that these additions have accumulated piecemeal, it is worth stepping back for a broad view of how these pieces work together. This section recaps the instrumentality of defining classes, consolidating the approaches acquired and expanding upon important topics where appropriate. To begin, a short summary of the fundamentals. A class is expressed in Python as a collection of function definitions contained within a codeblock. This codeblock is demarcated by the keyword class, followed by the name of the class ** and, optionally, an indication of a superclass. The functions contained in this codeblock become associated with objects, either as methods or properties. A special initialization method that is invoked when objects are first constructed takes the reserved name __init__, and is the conventional location for the declaration of class members. Other functions contained within the codeblock may be declared using decorators, the most common example of which are static methods...
eBook - ePub- Phillip D. Brooker(Author)
- 2019(Publication Date)
- SAGE Publications Ltd(Publisher)
...7 Building New Objects with Classes Classes 128 Working with classes 128 Class construction 130 Class instances 131 Using classes to build an academic referencing tool 132 Classes in action 140 Chapter objectives Learn how to build your own objects in Python, to feed into more advanced programming tasks. 7.1 Classes So far, we’ve seen lots of different types of objects in Python (integers, floats, strings, lists, dictionaries, functions, etc.) and we’ve spent some time learning how to work with them. This belies Python’s role as an “object-oriented” programming language – everything in Python is an object, and arguments can be passed around from object to object for whatever purpose you like. However, we don’t just have to rely on the objects that Python delineates for us – we can create our own with classes. With classes, we can build “blueprints” or templates for new objects, which we can give new attributes and new methods (i.e. functions). The reasons why we might want to do this should become clear as we go through the code and through the “Classes in action” subsection below. For now, however, we might note that we could be working with many different kinds of data (i.e. object) in any given coding project – below, I talk about an example where I’m working with different types of social media data, for instance – and it doesn’t make sense to treat all these different types of thing as if they were the same (and as if we would want to perform the same kinds of functions on them). Hence, using classes, we can make distinctions between different types of object that we bring into Python, so that we can handle them appropriately. With classes we can collect new types of object together and work with them in repeatable ways on the basis that they share common properties. Working with classes Let’s look at how this works in code. Open the file called 7_1_1_Classes.py, execute it, and work your way through the script and the instructions therein...
- Yasha Hasija, Rajkumar Chakraborty(Authors)
- 2021(Publication Date)
- CRC Press(Publisher)
...The choice() function, every time it is executed, chooses an item from the list randomly. Throughout this book, we will use various packages to make the readers' learning experience more comfortable. Classes and Objects Procedural programming ensures that a program is split into a variety of functions. Data is kept in a set of variables, and the functions manage them. When the programs expand, we result in a bunch of functions in place. We often have to copy and paste the lines of codes over and over. Dependability of one function on other functions can break our code while modifying a core function. Object-oriented programming can also solve this problem. Through object-oriented programming or OOP, a set of associated variables and functions may be combined into a unit called an object. The object is made up of functions and variables. The functions present in an object are called methods. Two critical elements of OOP are classes and objects. A class is a template model for the creation of individual objects. For example, we can have an mRNA class, as all mRNAs have a few similar properties and functions. In OOP, any individual mRNA with an individual gene and sequence is an instance or object of class mRNA. In Python, integer, string, list, dictionary, and everything else constitute the “class”. That is precisely why when we use the type() function, we get the word “class” - implicating the class it belongs to. Functions within the class are called methods, and we have seen various methods in the previous sections. We first need to define a class using the keyword “class” to build our own custom object in Python. Consider creating objects to reflect the details of mRNA. Every object will be a single mRNA object. First, we have to create a class...
