Any fool can write code that a computer can understand. Good programmers write code that humans can understand. -- Martin Fowler, 1999
The purpose of this document is to make everyone's life easier.
It's easier when you read good, well-formatted, with a clearly defined purpose, code. But the only way to read clean code is to write such.
This document can help achieve that, but keep in mind that those are not silver-bullet, fix-all-at-once rules. Just think about readability while writing code. Write code like you would have to read it ten years from now.
Thrift has some history. Not all existing code follows those rules. But we want to improve over time. When making a small change / bugfix - like a single line fix - do not refactor the whole function. That disturbs code repository history. Whenever adding something new and / or making bigger refactoring
When in doubt - contact other developers (using dev@ mailing list or IRC). Code review is the best way to improve readability.
Finding proper names is the most important and most difficult task in software development.
For detailed information see lib/LANG/coding_standards.md