Software Design

Intro This is the 3rd part of the Low level design series. Where I will introduce you to design pattern. In this post we will talk about design patterns that I found most useful because they address some very common problems. So following are a discussion on design pattern with 6 design patterns you can start using right away. Prerequisite Design patterns are instantiations of SOLID principles in one way or another. Think of SOLIDs as specifications and design patterns are their implementation. Therefore, before reading this you should definitely read THIS article on solid principles. ...

TL;DR 1. Use design pattern only when you are absolutely sure about the problem it will solve. 2. Goal of design is to lay the abstractions of a system to reflect the problem space and hide implementation details under appropriate abstractions. 3. SOLID are guide lines to create coherent systems. 4. SRP: Function/class/module should do one thing and do it well 5. OCP: Modules should be open for extension but closed for modification. ( A bit confusing, so read it) 6. LSP: How to not misuse inheritance: Users of base class should not notice if you pass them an object of derived class. 7. ISP: Users should only conform to the part of interface that they use. 8. DIP: This is the most important one. It tells you how to decouple a system. It says depend of abstraction rather than concretion. ...

TL;DR Mistakes to avoid Shiping the code as soon as it works Assuming requirement of an abstraction to account for probable obscure use cases. Not slowing down in development process. ( A idea on how to slow down effectitely is mentioned below) Not knowing what cleaning the code means. ( Cleaning the code is neither adding comments nor renaming variables with longer names) Few Ideas to understand to avoid the mistakes 1. Complicated vs Complex systems: Complicated puts high cognitive load, Complex is big but it makes sense. 2. Slowdown in development phase to think about maintenance to make maintenance easy 3. Design is an iterative process. You switch between development and then design with every significant change to the system. 4. How to slow down: Go fast, implement –> Slowdown, create proper abstraction to model problem space 5. How to create proper abstraction: Integrate thinking framework of SOLID principles when thinking about abstractions of a system 6. A brief introduction to SOLID principles. ...