Inheritance and Composition

Inheritance and Composition are two ways to create a relationship between classes and objects in Object-Oriented Programming Languages. In this article we are going to understand how we can use it and when we should use Inheritance or Composition

Inheritance

Inheritance it’s a principle of the Object-oriented programming that allow the classes to share attributes and methods beyond ‘Inheritance’. This is useful to reuse code or behaviour. In .NET it’s not allowed to have multiple inheritance, so you can only inheritance from one class.

This is a definition of Inheritance from the Microsoft documentation:

Inheritance is one of the fundamental attributes of object-oriented programming. It allows you to define a child class that reuses (inherits), extends, or modifies the behavior of a parent class

In Inheritance, we have two types of classes, the Base class and theDerived class. The Base class is the class that give the characteristics to the other class. The **Derived class **is the class that inherited the characteristics from the base class.

Let’s see an example of Inheritance in a real-world scenario using C#. I have this class that is named as Entity. This is a generic class that has two properties, an Id and the date on which the entity was created. Every class that inherited from Entity, will also have access to this two properties. This is an abstract class because this class cannot be instantiated, it only can be inherited.

namespace BookStore.Domain.Models
	{
	    public abstract class Entity
	    {
	        public int Id { get; set; }
	        public DateTime CreatedDate { get; set; }
	    }
	}

#dotnet #oop #dotnet-core #csharp #dot-net-framework

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Types of Inheritance in Python | Python Inheritance [With Example] | upGrad blog

Introduction

The struggle for a clean code is a battle joined by all the programmers. And that battle can be conquered with a proper armour of object-oriented programming concepts. And proper utilization of OOP concepts helps us to improve code reusability, readability, optimal time and space complexity.

Coding in Python is super fun. It has a whopping number of library support, object-oriented, GUI programmability makes it a hot cake among all the programming languages.

Inheritance is one of the most utilized object-oriented features and implementing it in python is an enthusiastic task. So, let’s start now!

First things first let’s understand the definition of inheritance.

#data science #inheritance #inheritance in python #python #types of inheritance #types of inheritance in python

Exploring Inheritance and Composition in Dart & Flutter

UI structures actually utilize inheritance as a key tool to stay away from code excess, and the Flutter system is no exemption. All things being equal, when you compose Dart code that isn’t straightforwardly expanding the UI system, it is ideal to keep your inheritance chains shallow and favor piece when it bodes well.

There is a pattern in software development away from the profound, branching class trees mainstream with object-arranged languages. Some accept more current functional ideal models ought to altogether supplant OOP in the software plan. This leaves numerous with the possibility that inheritance is not placed in software development anymore, or that its utilization ought to be rigorously restricted.

In

this blog, we will be **Exploring Inheritance and Composition in Dart & Flutter. **We will take a look at how inheritance and composition patterns will work with dart and flutter in your flutter applications.

Table Of Contents ::

What is Inheritance in Flutter?

Types of Inheritance

Inheritance In Data Models

What is Composition in Flutter?

Use of Composition child pattern in Flutter

Composition In Data Models

Conclusion

What is Inheritance in Flutter?:

Inheritance is the capacity of a class to inherit properties and strategies from a superclass and the’s superclass, etc. It is exemplified in Dart by the @override metatag. With it, a subclass’s execution of inherited conduct can be particular to be proper to its more explicit subtype. It permits extending out a class to a particular adaptation of that class. As said before all classes acquire from the Object type, just by pronouncing a class, we expand the Object type. Dart permits a single direct legacy and has uncommon help for mixins, which can be utilized to extend class functionalities without direct inheritance, simulating various inheritances, and reusing code.

Mixins are a method of reusing a class code in numerous class hierarchies. To utilize a mixin, utilize the with a keyword followed by at least one mixin name. To indicate that lone particular sorts can utilize the mixin — for the model, so your mixin can summon a strategy that it doesn’t define — use on to determine the necessary superclass.

#inheritance #composition #dart #flutter

Types of Inheritance in Python

Introduction

The struggle for a clean code is a battle joined by all the programmers. And that battle can be conquered with a proper armour of object-oriented programming concepts. And proper utilization of OOP concepts helps us to improve code reusability, readability, optimal time and space complexity.

Coding in Python is super fun. It has a whopping number of library support, object-oriented, GUI programmability makes it a hot cake among all the programming languages.

Inheritance is one of the most utilized object-oriented features and implementing it in python is an enthusiastic task. So, let’s start now!

First things first let’s understand the definition of inheritance.

#data science #inheritance #inheritance in python #python #types of inheritance

Forms of Composition in JavaScript and React

One of the core ideas in functional programming is composition: building larger things from smaller things. The canonical example of this idea should be familiar with legos.

Multiple legos can be joined and yield another lego that can continue to be built on and attached to others. In functional programming, the basic unit for composition is functions and larger functions are built by connecting and combining smaller ones.

When asked how to handle a particular scenario, edge case, or requirement, a functional programmer will nearly always answer: ‘with a function’.

Object-oriented concepts like factories, strategy mangers, or polymorphism don’t have an equivalent in the functional paradigm. Functional programming has its own key concepts, composition is one.

A (quick) Aside

One distinction between functional and object oriented programming is best seen in the difference between

circle.area()andarea(circle). In the first version - a more object oriented style -areais a method that exists on theCircleclass and can only be called onCircleinstances. In the second,areais a function that accepts an object. Unlike the object oriented version, it can act on any object that conforms to the type expected byarea.

This illustrates a core difference between the two paradigms. In an object oriented world, data and functionality are coupled -

areais a function on instances ofCircleobjects limited to objects created by that class. In functional programming, data and functionality are decoupled -areais a function that can act on any object that has the required properties.

While object oriented patterns have interfaces, inheritance and other mechanisms for sharing behavior like calculating the area of various shapes, it can often feel like you’re standing in an abandoned abstract factory churning out reverse proxies* 🙃

*I’ve never written an abstract factory and this is just a cheeky line to maintain engagement. Like all things, OO is another tool to leverage when needed.

Forms of Composition

Functions are not the sole unit of composition and the principle extends beyond the domain of functional programming. ReactJS uses components as a unit of composition. Hooks too like

useStateare another unit. If you’re really focusing, you may notice that hooks are just regular functions which is why they are great for composition.

Its possible to build larger components from smaller components, and write custom hooks that extend the capability of existing hooks.

Composition relies on recursion to build larger abstractions from smaller abstractions but with each abstraction layer as the same type as all the others. Once a compositional unit like functions or components exist, you immediately get a compositional model that allows for building high level abstractions very quickly for free. Each layer of abstraction is fundamentally the same type of thing as all the other layers.

An Example of (Functional) Composition

Let’s begin with three functions.

const toUpperCase = str => str.toUpperCase();
const appendExclamationPoints = str => str + '!';
const split = str => str.split('');

Often code takes the output of one function and uses it as the input to another. This is the idea of a pipeline. Data in, data out.

split(appendExclamationPoints(toUpperCase('hello world'))) 
// ["HELLO", "WORLD!"]

While the above works, it isn’t the easiest to read. A simpler abstraction is a single function that can be invoked with some string passed as the parameter.

function appendExclamationPointAndSplitOnSpace(someString) {
    return (someString.toUpperCase() + '!').split();
}

appendExclamationPointAndSplitOnSpaceagic('hello world') 
// ["Hello", "World!"]

The above function, while meeting the requirements perfectly, isn’t necessarily clean code. It uses an imperative style, specifying each operation to perform to get the desired result. While it may be simple enough to read and understand, a more declarative style would be even easier.

Functional programming can help simplify the above through a helper function called

compose. Compose accepts an arbitrary number of functions, and returns a new function that runs each of the functions passed in such that the output of the previous functions is used as the input to the next

t appendExclamationPointAndSplitOnSpace = compose(
    split, 
    appendExclamationPoints, 
    toUpperCase
);

appendExclamationPointAndSplitOnSpace('hello world') 
// ["Hello", "World!"]

Note that the functions execute in a right to left wrapping manner similar to the original example. That is,

splitinvokes the result ofappendExclamationPointswhich invokes the result oftoUpperCase. This results in a declarative style, with no direct function calls or references to the data and methods that exist on the data type. A new function is created that accepts the data and computes the result. Most importantly, we’re able to build the new function from existing smaller functions that we already have or are trivial to write.

Composing functions requires adherence to the following intuitive rule. The output type of function A must match the input type of function B given that B runs with the output from function A. In a practical example, if a function that returns a number is composed with a function that expects a string, some unexpected errors might creep in.

Various implementations of

composecan be found in Lodash, Redux, and other JavaScript libraries. Its certainly not magical, and can be written in under 10 lines.

#functional-programming #javascript #reactjs #composition #pure-functions #compositions-in-javascript #compositions-in-react #javascript-top-story

Inheritance in Python | Python Inheritance [With Example]

Python is one of the most popular programming languages. Despite a transition full of ups and downs from the Python 2 version to Python 3, the Object-oriented programming language has seen a massive jump in popularity.

If you plan for a career as a Python developer, you are bound to have a higher payout. As the average salary for a Python developer is around $119,082 per year. But, before you go ahead with the Python learning program, here is something that you should know first- Inheritance in Python.

Let’s first begin with what exactly is inheritance in Python?

What is an inheritance in Python?

Just like a parent-child relationship, inheritance works on derived classes relative to the base class. Every “Derived” class inherits from a “Base” class. The inheritance is represented in UML or Unified Modeling Language. It is a standard modeling language that includes an integrated set of diagrams to help developers specify, structure, and document software systems elements.

Inheritance relationship defines the classes that inherit from other classes as derived, subclass, or sub-type classes. Base class remains to be the source from which a subclass inherits. For example, you have a Base class of “Animal,” and a “Lion” is a Derived class. The inheritance will be Lion is an Animal.

A “Lion” class inherits

• Interface
• Execution

Note: You can replace the Derived Class objects with Base Class objects in an application known as the Liskov substitution principle. It indicates that if a computer program has object P as the subtype of Q, you can easily replace P with Q without altering the properties.

#data science #inheritance #inheritance in python #python