If you need more than 3 levels of indentation, you’re screwed anyway and should fix your program.
— Linus Torvalds in Linux 1.3.53 CodingStyle documentation (1995). Retrieved on 2011-08-13. - 1995-99
- constraining how much you nest, forces you to write better code
- deeply nested code often violates of single responsibility principle
Extract into its own function
Extract inner parts of loop, conditions or if statements into its own function
Function calculate something
Loop over field
If element is even
Modify element
Endif
Endloop
Endfunction
Function filter even numbers
If element is even
Modify element
Endif
Endfunction
Function calculate something
Loop over field
Call filter even numbers
Endloop
Endfunction
Invert happy and unhappy paths
Rearrange your conditions and put your happy path at the end of functions
Function calculate something
If parameter invalid
Throw error 😡
Else
If another unhappy condition
Return nothing 😡
Else
Happy path 🙂
Endif
Endif
Endfunction
- Happy path is hard to identify and deeply nested
Function
If parameter invalid
Throw error 😡
Endif
If another unhappy condition
Return nothing 😡
Endif
Happy path 🙂
Endfunction
- Deal with unhappy or exceptional path cases first
- Identify unhappy paths using early exists or short circuits
- Error paths are indented and can be mentally discarded
- Start your function with a flat list of conditionals
- Happy path moves down the function
Avoid nesting the happy pay in many conditions
Inspiration
| Video | Information |
|---|
Sources:
- 2023-03-22: Why You Shouldnt Nest Your Code
- 2023-03-22: Why you should reduce nesting blocks in your code, with practical refactoring tips | by Brook Novak | Medium
- 2023-03-22: Replace Nested Conditional with Guard Clauses
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