Clean Code summary

By: Jan de Vries E-mail: [email_address]

Title: Clean Code A Handbook of Agile Software Craftmanship Author: Robert C. Martin Pages: 349 Chapters: 17 Target Audience: Developers Slides: 29

Awareness Tips on how to produce better code Readability The ‘boy scout rule’ Starting out with tips and examples Later on real world examples It’s not the bible!

Smart developer Difficult code Has great developing skills r = lowercase url Professional developer Readable code Maintanable code ‘ Clarity is king’ lowercaseUrlOfCurrentPage = lowercase url

Seiri – Organize/Sort Seiton – Systemize/Tidiness Seiso – Cleaning Seiketsu – Standardization Shutsuke - Discipline

Go fast? Angry boss? Tired of project? Get working now, clean up later? Everybody does it!

Redesign of system Everybody wants in Everything the old system does + better Takes a long time Team members leave

Requirements change and not meet design Schedules too tight Stupid managers Intolerant customers Useless sales

They ask us for information If they don’t, make yourself noticed Users ask us if requirements fit the system Project managers ask us to help with schedule

Take your time Not theList Searchable names Constants Hungarian Notation IDE Member prefixes Interfaces

Mental mapping i, j, k, l Pronouncable 1 word per concept Get, retrieve, fetch Controller, manager, driver Use domain names Read by programmers

Small < 150 characters per line < 20 lines Blocks, indenting 1 thing! Arguments Side effects Prefer exceptions

Extract try-catch Error handling is 1 thing Don’t repeat Not all at once

Don’t Self-explaining If you can’t do any better Clarification Warning TODO

Redundant Misleading Noise Copy-pasting Use a function or variable Closing brace comments Commented out code Version control!

Variable declarations Where they are used Instance variables Top of class Dependancy Top-down Not 1-line functions Team rules 10 minutes IDE formatter

Law of Demeter Method f of a class C should only call the methods of these: C An object created by f An object passed as an argument to f An object held in an instance variable of C Objects Data structures

Narrow down exceptions Provide context Don’t return null; Don’t pass null Prevents null-checking

Exploring & learing Experiment & learn Reading manual Using non-existing code Interface Write your own

Three laws of TDD You may not write production code until you have written a failing unit test You may not write more of a unit test than is sufficient to fail, and not compiling is failing You may not write more production code than is sufficient to pass the currently failing test

Keeping tests clean Maybe more important as actual code No fear of refactoring One assert per test Single concept per test

F.I.R.S.T. Fast Independent Repeatable Self-validating Timely

Should be small Single Responsibility Principle SQL  Select, Update Easy to change code

Start small Add features later

Keep synchronized blocks small Don’t share objects Suspicious failures Are bugs, not cosmic glitches

Start with bad code and clean it Keeping things small Keeping code readably Self-explaining Standards Unit testing Interfaces, abstract classes, OO You are responsible!

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