ryenski

Ruby OOP Cheat Sheet

Practical object-oriented design for Ruby, drawn from Sandi Metz (Practical Object-Oriented Design in Ruby, 99 Bottles of OOP) and SOLID. Use it to keep change cheap, not to decorate code with patterns.

Pronounce POODR “pooder.”

---

The point

ryenski

LazyVim Jump commands

These assume your setup: LazyVim with the Ruby extra, ruby-lsp, the Snacks picker, treesitter text objects and flash. You don't have vim-rails installed, so there's no :A or gf jumping between related Rails files.

LSP (ruby-lsp)

Key	Jump
gd	Definition of the constant or method under the cursor

ryenski

#!/usr/bin/env bash
set -euo pipefail

mode="${1:?usage: git-guard.sh pre|stop}"
input="$(cat)"

project_dir="${CLAUDE_PROJECT_DIR:-$(jq -r '.cwd' <<<"$input")}"
session_id="$(jq -r '.session_id // "default"' <<<"$input")"
state="$(cat "$project_dir/.claude/.tdd/$session_id" 2>/dev/null || echo none)"

ryenski

Error Reporting Patterns

We use Rails' native error reporter (Rails.error) as the single interface for all error and exception reporting. It replaces our previous Honeybadger-specific calls and routes through our RailsErrorSubscriber, which forwards to Rails.logger and the OTel pipeline.

---

The three APIs

Method	When to use

ryenski

Grips Codebase — Tech Debt Analysis

Generated: March 30, 2026
Codebase size: ~1,118 app files, 274 models, 207 controllers, 264 services, 950 tests

---

1. Dead / Orphaned Code

These files exist but are never referenced outside themselves. Safe to delete after confirmation.

ryenski

require 'redcarpet'

module MarkdownHandler
  def self.erb
    @erb ||= ActionView::Template.registered_template_handler(:erb)
  end

  def self.call(template, source)
    _frontmatter, markdown = Page.parse_frontmatter(source, raw: true)
    compiled_source = ActionView::OutputBuffer.new(erb.call(template, markdown)).to_s

ryenski

require 'redcarpet'
require 'redcarpet/render_strip'

module MarkdownHelper
  def markdown(str)
    html_renderer.render(str).html_safe
  end

  def plain_text(str)
    strip_down_renderer.render(str).html_safe

ryenski

I18n Best Practices

Use human-readable keys

Prefer natural language over abstracted strings for language keys. This helps to make the views easier to read and understand.

Take advantage of the fact that spaces are legal in YAML keys:

Examples

# Bad
t('.all_label')

ryenski

desc 'Raise exception if used in production'
task protect_prod: [:environment] do
  raise 'This task cannot be run in production' if Rails.env.production?
end

['db:drop', 'db:reset', 'db:seed'].each do |t|
  Rake::Task[t].enhance ['protect_prod']
end

ryenski

To convert json to csv with headers using jq and the @csv filter.

jq -r '[first|keys_unsorted] + map([.[]]) | .[] | @csv' example.json > converted.csv

This would work on a simple json structured like:

[