Programming Concepts - Design Patterns (Creational, Structural and Behavioral)

Summary

In this video, Alex Forsyth introduces the concept of design patterns in computer science, drawing parallels with city planning. He explains how these patterns, categorized into creational, structural, and behavioral, can be applied to object-oriented programming to solve problems efficiently. Creational patterns focus on object instantiation, structural patterns on combining objects to form larger structures, and behavioral patterns on the interaction between objects. The video aims to provide a foundational understanding of these patterns, with individual patterns to be explored in future videos.

Takeaways

• 📚 The video discusses the concept of design patterns, popularized by the book 'Design Patterns: Elements of Reusable Object-Oriented Software', commonly referred to as the 'Gang of Four' book.
• 🏛️ Design patterns are categorized into three main types: creational, structural, and behavioral, each serving different purposes in object-oriented programming.
• 💧 An example of a creational pattern is the factory method, which provides a way to create objects without specifying the exact class of object that will be created.
• 🐅 The factory method can be used to create a common interface for creating different types of objects, such as various kinds of animals, without redefining properties and methods for each type.
• 🚢 Another example given is the use of a logistics interface object to handle different types of shipping operations, like shipping by boat or by truck, which illustrates the application of design patterns in real-world scenarios.
• 🧱 Structural patterns focus on composing structures by identifying simple ways to build complex systems out of objects that interact with one another.
• 🔄 Behavioral patterns are concerned with the interactions between objects, such as how a 'bottled water' object interacts with an 'Alex' object, affecting properties like thirst levels.
• 🔑 The video emphasizes the advantages of using design patterns in programming, such as reusability and the ability to solve common problems efficiently.
• 🔍 The speaker, Alex Forsyth, uses the analogy of city planning to explain the application of design patterns in object-oriented programming, suggesting a structured approach to problem-solving.
• 🎯 The video aims to introduce the concept of design patterns and their importance in programming, with a promise to cover individual patterns in more detail in future videos.
• 👋 The script concludes with a friendly sign-off, wishing the viewers a great day and encouraging them to enjoy the content.

Q & A

What is the main topic discussed in the video script?

The main topic discussed in the video script is design patterns in computer science, specifically their application in object-oriented programming.

What is the origin of the term 'design patterns' in computer science?

The term 'design patterns' in computer science was popularized by a book often referred to as the 'Gang of Four' book, which categorized different design patterns.

What are the three categories of design patterns mentioned in the script?

The three categories of design patterns mentioned are creational, structural, and behavioral.

What is an example of a creational design pattern mentioned in the script?

An example of a creational design pattern mentioned is the factory method, which provides a template for creating objects.

How does the factory method help in object creation?

The factory method helps in object creation by providing an interface for creating objects, allowing for the creation of different versions of objects without redefining their properties and methods each time.

What is the purpose of structural design patterns?

Structural design patterns are used to create new objects by combining existing objects, allowing for the building of larger structures from smaller components.

Can you provide an example of how structural design patterns work?

An example of structural design patterns is assembling a bottle of water using separate objects for the plastic bottle, the water, and the cap, and then combining them to form a complete product.

What are behavioral design patterns concerned with?

Behavioral design patterns are concerned with the interactions between objects, how they affect each other's properties and methods.

How do behavioral design patterns solve problems?

Behavioral design patterns solve problems by defining how objects interact with each other, affecting their properties and methods, which can be used to model complex interactions.

What is an example of a behavioral design pattern scenario given in the script?

An example given in the script is a 'bottled water' object interacting with an 'Alex' object, where drinking from the bottle affects both the water level in the bottle and Alex's 'thirst' property.

What is the significance of understanding design patterns in programming?

Understanding design patterns in programming is significant as it allows developers to solve common problems more efficiently by reusing proven solutions, promoting better software design and maintainability.

Outlines

00:00

📚 Introduction to Design Patterns in Object-Oriented Programming

In this paragraph, Alex Forsyth introduces the concept of design patterns, a term popularized by the book 'Design Patterns: Elements of Reusable Object-Oriented Software', often referred to as the 'Gang of Four' book. The speaker explains that design patterns are templates for solving common problems in object-oriented programming by categorizing them into creational, structural, and behavioral patterns. The paragraph sets the stage for a deeper dive into these categories, emphasizing the importance of understanding how objects can be used effectively to solve programming problems.

Keywords

💡Design Patterns

Design patterns are standardized solutions to common problems in software design. They are formalized templates that can be applied to specific scenarios to solve particular design issues. In the context of the video, design patterns are applied to object-oriented programming to categorize and solve problems efficiently. The script mentions that design patterns are divided into creational, structural, and behavioral categories, which help in organizing and understanding the different approaches to problem-solving in programming.

💡Object-Oriented Programming

Object-oriented programming (OOP) is a programming paradigm that uses objects, which can contain data in the form of fields and code in the form of methods. It is about creating programs by organizing software components into objects that interact with one another. The video script explains OOP by using the example of a 'bottle of water' object, which has properties like the amount of water and methods like opening the cap, illustrating how objects can be used to model real-world entities in software.

💡Properties

In object-oriented programming, properties are attributes of an object that describe its characteristics. The script uses the example of a 'bottle of water' object, where the property could be 'how much water is in it,' which describes the state of the object. Properties are key to defining what an object is and how it can be represented within a program.

💡Methods

Methods in OOP are functions or procedures that are associated with an object and define the actions it can perform. The script refers to methods as 'functions' that an object can have, such as the function to 'open it up' for the 'bottle of water' object. Methods are the behaviors of an object, defining how it can interact with other objects or the environment.

💡Classes

A class in OOP is a blueprint for creating objects. It defines the properties and methods that an object of that class will have. The script mentions creating a 'bottle of water' class, which serves as a template to create multiple 'bottle of water' objects with predefined properties and methods. Classes are fundamental to OOP as they allow for the instantiation of multiple objects with the same structure.

💡Instantiation

Instantiation is the process of creating an instance of a class. In the script, after defining a class for a 'bottle of water,' the process of creating individual bottles of water from that class is referred to as instantiation. It is how programmers create specific objects based on a general class blueprint.

💡Creational Patterns

Creational patterns in design patterns are concerned with object creation mechanisms, trying to create objects in a manner suitable to the situation. The script discusses the 'factory method' as an example of a creational pattern, which provides a way to defer instantiation to child classes, allowing for more flexible object creation, such as creating different types of animals without redefining their properties and methods each time.

💡Structural Patterns

Structural patterns deal with the composition of classes and objects to form larger structures, while keeping them flexible and efficient. The script uses the example of breaking down a 'bottle of water' into separate objects like the 'plastic bottle,' 'water,' and 'cap,' and then assembling them to form the complete object. This illustrates how structural patterns can help in building complex systems by combining simpler objects.

💡Behavioral Patterns

Behavioral patterns are concerned with the interactions between objects, focusing on the ways in which they communicate and assign responsibilities to each other. The script describes a behavioral pattern with the interaction between the 'bottled water' object and an 'Alex' object, where drinking from the bottle affects both the water level and the 'thirst' property of Alex. Behavioral patterns help in defining how objects will operate in conjunction with one another.

💡Interface

In OOP, an interface is a completely abstract class that contains only abstract methods and constants. The script refers to creating an 'animal' interface, which could be used as a template for creating different types of animals, ensuring that all animals have the same structure for properties and methods like making a sound. Interfaces are used to define a contract that implementing classes must follow, providing a way to create a family of related objects with consistent behavior.

💡Logistics Interface

The term 'logistics interface' in the script refers to the application of an interface in the context of logistics operations. It is used to illustrate how an interface can define a common structure for different types of shipping methods, such as shipping by boat or by truck, while allowing for specific behaviors and properties unique to each shipping method. This demonstrates how interfaces can be used to create a unified approach to handling different but related scenarios.

Highlights

Introduction to design patterns in object-oriented programming.

Design patterns popularized by the book 'Design Patterns: Elements of Reusable Object-Oriented Software'.

Design patterns categorized into creational, structural, and behavioral.

Objects as templates for properties and methods in programming.

Example of a 'bottle of water' object with properties and methods.

Instantiation of objects from a class for multiple individual instances.

Utilizing object creation to solve programming problems through patterns.

Explanation of the 'factory method' as a creational design pattern.

Application of design patterns in logistics operations with different shipping methods.

Structural design patterns focus on how objects work together.

Example of assembling a 'bottle of water' from separate objects.

Behavioral design patterns define how objects interact and affect each other.

Impact of a 'bottled water' object on 'Alex's' property of 'thirst'.

Importance of understanding how objects affect each other's properties and methods.

Overview of individual patterns within each category used for problem-solving.

Introduction of the concept of design patterns in this video.

Encouragement for viewers to have a great day and enjoy the content.

Transcripts

[Music]

hey right this is Alex Forsyth Mouse

Rosetta coded off town with some more

computer science concepts and knowledge

and they don't meet all my design

patterns now design patterns are a

concept I got popularized by a book that

oftentimes people just shorthand

referred to as a gang before book okay

really was just for authors I decided to

take the idea of design patterns and

sort of like city planning and you know

if City Planning or urban planning and

then apply it to sort of object-oriented

programming and saying okay there's

different ways there's different

patterns for solving problems using

objects and kind of put all these design

patterns into different categories and

that's we're gonna talk about today the

different categories so again objects

are sort of just templates for a series

of properties and methods but you may

use your programming so in that case I

might have a bottle of water object okay

in the bottle of water will have a

property how much water isn't it so

houses it would have a function goes in

it you know to open it up so that'd be a

method where I woulda spread how it's

been up the model and then that can

create as many once I create that object

that class I can then instantiate or

create as many individual bottles of

water that I want but knowing that I can

do that in programming now knowing that

I can create objects how can I take that

to an advantage and create patterns

that'll help solve some problems in

programming and we divide these patterns

up into three categories creational

structural and behavioral now creational

has to do with how we create objects are

like how so a problem I have is every

time I have to create a another animal I

have to create every all these things

from scratch have to redefine the like

property I have to redefine to the sound

proper sound method you know even though

I know all animals make a sound pigs

don't Lincoln cows go Moo I have to

redefine this method every time what is

my solution okay one one solution could

be something called like a factory

method and we'll go through all these

individual design patterns but the idea

is you might create how what is the

method we're going to use to create

objects so maybe we create that

interface that sort of template object

for animal

from which I can create how tiger pig

cradle these animals from that have all

these properties and methods built in

already and that'll make it easier for

me to create different versions which

for animals conceptually make sense but

practicality you're like so what would I

need that you know good examples like

maybe you have different types of

logistical operations that generally

have the same sort of underlying

structure but shipping you know but just

jewel is this your logistics shipping

buy a boat are gonna be different

analytics by shipping by truck so you

can create sort of a logistics interface

object and then create different

instances with the separate differences

then there's structural be design

patterns which are left about how do I

create new objects but creating objects

that work together to create something

so in this case if I were to break this

down and create a bunch of separate

objects like this the plastic bottle the

water is an object and the cap as an

object and then basically use those

three objects to assemble a bottle of

water that's another way I can kind of

break down a problem solve it by

breaking it down into even smaller

objects with properties and methods and

then take those objects and assemble a

new object so it's about building bigger

things from smaller things structural

behavioral has to do with sort of how

does interact how to do different house

different objects affect each other's

variables and whatnot so in this case is

bottled water when I drink it this

bottled water object is now interacting

with the object of Alex and basically

now my property of thirst is going down

okay so this bottled water has an effect

on my thirst property but now I have an

effect on its level of water property it

has less water so basically by defining

how these different objects affect each

other and how they can change each other

property is how their methods affect

each other that's more of a behavioral

design pattern using behavioral design

patterns you can solve problems by

defining how objects work with each

other so again how do we create the

product how we're doing create the

object creational patterns

how do we use objects to create other

objects structural patterns and how do

objects affect or interact with each

other behavioral patterns now there's a

lot of individual patterns within each

of these categories that are used over

and over again different problems

solving and we'll go over those in

different videos but I just want to

introduce the concept here in this video

so you guys have a great day and enjoy