Clean Code Notes

It is hard to find software engineer these days that has never heard of Clean code. At the same time in many organizations code that runs on production brings bugs and pain every day.

So, what is Clean code and why it is important?

Clean code is set of principles for writing clear, understandable, and maintainable code. It is not strict rules and applying each principle needs to make sense in concrete situation.

Two main reasons to use Clean Code principles are:

decreasing the cost of maintenance and support of software - easier to make changes, add new functionalities and find defects
making life of software engineers simpler.

There is a list of principles that I use frequently.

1. Meaningful names of variables

one word per concept
classes and objects should have noun or noun phrase names
readable and searchable

2. Small methods

one level of abstraction per method
method should do one thing

3. Avoid flag argument

create separate methods, should be a part of API
more about FlagArgument on Martin Fowler’s blog

4. Command query separation

each method should be only command or query
command performs an action, do not return anything and has a side effect
query returns a value, does not perform an action and does not have a side effect

5. DRY – do not repeat yourself

create helper method

6. Null, do not pass, do not return

use Null object pattern (needs to be passed through the system without consequences)

7. Clean tests

one assertion per test
DAMP (descriptive and meaningful phases) over DRY

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