Objects, attributes, maps, oh my

Dynamically typed languages like Python, Ruby, and JavaScript typically store object attributes using hash tables, which while functionally simple, perform poorly due to slow hashing operations and memory indirection. Runtime implementors optimize this through "shapes" or "hidden classes" that store attributes inline on objects, significantly reducing CPU instructions and memory access for the common operation of attribute access. The article examines how this optimization technique works in practice with a focus on implementable code examples.