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Codemotion 2017: clean-code-design-principles-kata

Materials and samples for my workshops on Clean Code and Design Principles


Codemotion 2015: Clean Code and Design Principles in Action: develop quality applications, faster

In Short

As developers, we often feel that we are always asked for more: more features, more bugfixes, more code to get our application done, faster. In the workshop you'll learn first hand how applying Clean Code and Design Principles will help you complete solid & maintainable applications in less time.





We are often asked for more features, more bugfixes, faster. But is "running" always the fastest way to get things done? For a mountain climber, "running" means more mistakes, falling off more often,thus proceeding more slowly. So like a climber gets to the top through a continuous chain of small, safe steps, we can improve coding by making design & implementation steps clean, safe and incremental. In the workshop, starting from concrete examples, you will learn first hand how applying Clean Code and Design Principles will help you complete more solid & maintainable applications in less time


Laptop Web Browser (Chrome or Firefox) Text Editor (Sublime, Atom, Visual Studio Code,...) and/or IDE (Eclipse, NetBeans, Intellij, Visual Studio,.. )


How does our code become unmanageable? A practical example

  • fast-forward demo through the life of an (apparently) trivial function
  • the effects: code-writing time vs application-ready time
  • what happens after 6 months?
  • why this happens? the "deadly sins" of development (cut & paste, optimization lust, haste, false savings, naming avarice, trial and error wrath, my code is perfect pride, making it right is too hard - discouragement)

What can we do about that?

Clean Code, Design Principles and Lean to the rescue

  • improving our code
  • improving our design
  • practice, practice, practice and continuous / daily improvement (Kaizen)

Clean Code by example: key concepts

Concept 1 - Naming

-reading code vs writing code

  • what is a good name?
  • same but different: the importance of conventions
  • be meaningful
  • aside: commit messages

Concept 2 - Formatting

  • making code readable
  • making code diff-friendly & commit-friendly
  • making code modification-friendly

Concept 3 - What's in a good function?

  • single responsibility
  • separing inputs from outputs
  • if you have to do 3 things, make 4 functions
  • primitives and orchestrators

Concept 4 - What's in a good class? Design Principles

  • Single Responsibility Principle
  • collaborating with other classes
  • composition vs inheritance (and the Open/Closed principle)
  • Dependency Injection
  • interfaces and the importante of Contracts

Concept 5 - Making our code Testable

  • avoid statics
  • testable code vs good design

Concept 6 - Making debug and troubleshooting easier

  • one task - one statement
  • make return values visible
  • logging

Concept 7 - Refactoring

  • from bad code to good code
  • in steps
  • learn your IDE refactoring tools
  • The "Boy Scout Rule"
  • Why we need unit tests?


Rewriting the initial example in a cleaner way

The principles

So what did we just do? Understand the principles

  • the relationship between quality and productivity
  • the need for a continuous chain of small, safe steps of design & implementation

Incremental development and evolutionary design

  • how to do everything incrementally
  • Separation of Concerns in practice: ask yourself questions!
  • incremental implementation: in-application Mocks & the Walking Skeleton approach
  • how to keep track of what you do and what is missing
  • how to manage incremental commits

A more complex example - applying the method to real-world problems

  • the feedback loop
  • splitting the problem
  • getting more feedback
  • getting feedback more frequently
  • model the problem
  • avoid trial and error, but if you need it, do it fast

How to continue by yourself: references for further learning

  • Principles of Package Design
  • More on TDD

For each module, hands-on lab will include

  • quizzes (which of these variants is better? trade-offs)
  • interactive examples to complete and modify in an online IDE


Basically, to all developers! Independently from the language / platform you are developing on, and from your expertise level, if you are interested in improving your approach to coding, and develop higher quality applications with more productivity, this workshop is for you.


Working knowledge and practical experience in one programming language (you should be able to write/compile/test/debug by yourself a program which reads and parses input and presents output either on the command line or in a simple GUI). Basic knowledge of HTTP.


Slides and Labs of Workshop on Clean Code and Design Principles in Action



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