Today I Learned

TIL, 2018-12-17, Immutability in Ruby


  • inch on recommendations for documentation. It also has CI.
  • deep_freeze freezes Ruby objects - good to look at the code on how it does that.
  • Almost every gem has config commands and parsers for those config commands. Really cool to think about.

A Review Of Immutability In Ruby


  • When two or more objects use the same piece of mutable data, they all have the ability to break each other in ways that can be hard to debug.
  • Standard lib’s freeze: prevents further modifications to obj. A RuntimeError will be raised if modification is attempted.
  • This will work on all objects except BasicObject.
  • Reassigning a constant variable will generate a warning, but mutating a constant value will not. You have to actually freeze the constant. Problem is, it’s shallow, so the existing elements can actually still change.
  • String literals are also immutable, just like numbers and symbols.
  • Recursively freezing an object property?
  • values gem

This project is maintained by daryllxd