Artem Yegorov

Namespaces 101

Introduction

Ruby has recently merged namespaces as an experimental feature that is disabled by default, as of this writing.

This is a non-trivial development driven by @matz himself, and mainly implemented by @tagomoris, who just became a Ruby committer (🎉).

The feature has been cooking for a long time, with a first ticket opened a couple of years ago (#19744) and a revised one opened just last week (#21311).

Make Ubuntu packages 90% faster by rebuilding them

TL;DR

You can take the same source code package that Ubuntu uses to build jq, compile it again, and realize 90% better performance.

Setting

I use jq for processing GeoJSON files and other open data offered in JSON format. Today I am working with a 500MB GeoJSON file that contains the Alameda County Assessor's parcel map. I want to run a query that prints the city for every parcel worth more than a threshold amount. The program is

You MUST NOT try and generate a Rails app from scratch on your own by generating each file. For a NEW app you MUST use rails new first to generate all of the boilerplate files necessary.
Create an app in the current directory with rails new .
Use Tailwind CSS for styling. Use --css tailwind as an option on the rails new call to do this automatically.
Use Ruby 3.2+ and Rails 8.0+ practices.
Use the default Minitest approach for testing, do not use RSpec.
Default to using SQLite in development. rails new will do this automatically but take care if you write any custom SQL that it is SQLite compatible.
An app can be built with a devcontainer such as rails new myapp --devcontainer but only do this if requested directly.
Rails apps have a lot of directories to consider, such as app, config, db, etc.
Adhere to MVC conventions: singular model names (e.g., Product) map to plural tables (products); controllers are plural.
Guard against incapable browsers accessing controllers with `allo

How to set up a basic Sinatra + React webapp in 2025

Let's say you want to use Ruby for the backend of a basic webapp but React on the frontend. Here's how.

(Note: All tested on January 13, 2025 with Ruby 3.3, Sinatra 4.1.1, and React 18.3. Configs may change over time.)

First, create the app folder and set up Sinatra:

mkdir my-sinatra-react-app

Implementing Advisory Locks in SQLite3

In my Rails model, I initially had a function to handle advisory locks in PostgreSQL. Here's the code, which works as expected:

# Postgresql version
def with_advisory_lock
  self.class.connection.execute("SELECT pg_advisory_lock(#{self.id})")
  yield

	# Usage:
	#
	# class Post < ApplicationRecord
	# include HasNanoid
	# has_nanoid
	# end
	#
	module HasNanoid
	extend ActiveSupport::Concern

	require "digest"
	require "rack"

	# This class encapsulates a unit of work done for a particular tenant, connected to that tenant's database.
	# ActiveRecord makes it _very_ hard to do in a simple manner and clever stuff is required, but it is knowable.
	#
	# What this class provides is a "misuse" of the database "roles" of ActiveRecord to have a role per tenant.
	# If all the tenants are predefined, it can be done roughly so:
	#
	# ActiveRecord::Base.legacy_connection_handling = false if ActiveRecord::Base.respond_to?(:legacy_connection_handling)

	class FuzzyIndex
	def initialize
	@index = Hash.new { \|h, k\| h[k] = Set.new }
	end

	def []=(key, value)
	trigrams(key).each { @index[it] << [key, value] }
	end

	def [](query)

	<%= form_with model: citizen, class: "card flex flex-col gap", data: { controller: "form" } do \|form\| %>
	<div class="flex flex-col gap mb-2">
	<div class="flex flex-col gap-half">
	<% countries = Country.order(:name) %>
	<%= label_tag :country_id, "Country", class: "text-sm font-medium leading-none" %>
	<%= select_tag :country_id, options_from_collection_for_select(countries, :id, :name, citizen.country_id), include_blank: "Select one", class: "input", data: { action: "form#submit", form_submitter_param: "on_country_change" } %>
	</div>

	<div class="flex flex-col gap-half">
	<% states = State.where(country_id: citizen.country_id).order(:name) %>

	# config/initializers/phlex_template_handler.rb
	require "action_view"
	require "phlex"

	# Intercept unknown "capitalized" method calls (e.g., PageView(...)) in templates,
	# look up a Phlex component class, instantiate it, and render it.
	# Crucially, we re-bind the user’s block so that `self` is the component, not the ActionView context.
	module PhlexDynamicMethodCalls
	def method_missing(name, args, *kwargs, &block)
	# Only intercept method calls starting with an uppercase letter (e.g. "PageView", "MyComponent", etc.)