Ruby object model, blocks, and enumerables

Reason about objects, modules, method lookup, blocks, Enumerable, immutability, exceptions, and idiomatic APIs before relying on framework conventions. Prefer transformations with explicit return values and isolate mutation at clear boundaries.

Production practice

Refactor a mutable reporting loop into a deterministic Enumerable pipeline with explicit failure behavior.

Treat conventions as defaults that make the common path clear—not as substitutes for explicit domain rules, authorization, database integrity, failure handling, measurement, or tests. Be prepared to explain the boundary, expected failure modes, and the evidence that the design works.