sambostock

Heredoc Indentation Cop

This is a scrappy implementation of a cop that checks the following for heredocs:

• Contents may only be indented in increments of 2 spaces.
• Contents may not be indented using spaces.
• Lines may be at max indented 2 spaces more than the line before, ignoring blank lines.

Usage

1. Copy heredoc_internal_indentation.rb to wherever you want in your project

sambostock

Overview

Say you're trying to consume a streaming API using Faraday. And say you need to consume the content line-by-line.

Let's explore one way of doing that.

How it works?

1. Faraday allows setting .options.on_data on the request to a Proc to run as data is streamed.

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I was curious what the smallest margins were by which candidates had won, and one thing lead to the next...

Data from https://rtr.elections.on.ca/RealTimeResults/en/electoral-district. Thanks for the open endpoints!

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require 'minitest/autorun'

module ForbidSubclassingIfTestMethodsDefined
  DuplicateTestsError = Class.new(StandardError)
  def inherited(klass)
    unless runnable_methods.empty?
      raise DuplicateTestsError, "Do not inherit from #{self}, as the tests it defines would be duplicated in #{klass}"
    end

    super

sambostock

Raffle Ractor

RubyConf 2020 held a puzzle-raffle in which the puzzle required using brute force to figure out the cleartext which produced a given hash.

Problem Description

If you process payments with Braintree you’ve likely seen a unique id that looks something like a1b2c3d4. This id goes by different names at different places but is often a way for a company to create a massive numbering system. Assuming an alphabet of only lower case letters and digits, the system above could be used for (26 + 10) ^ 8 = 2,821,109,907,456 combinations. That is an enormous number! Some places, including Braintree, also choose to encode some information in these ids. Without going too much into the Mathematics of hashing and encoding algorithms we can say that it’s possible to take some information, let’s say an email or url, add some other information, say a 5 character raffle number 😉, and encode that information into a fixed length String. If you know the unique id and you have the fixed length encoded Stri

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explicit_receiver = Object.new
def explicit_receiver.setter=(error)
  puts "setter= called with #{error.class}"
end

begin
  1 / 0
rescue => explicit_receiver.setter
  # There doesn't seem to be a restriction on rescue setting local variables.
  # Ruby seems to take whatever appears in the rescue clause

sambostock

# frozen_string_literal: true

Dev = Struct.new(:name, :senior, :prefers_consecutive_shifts, keyword_init: true) do
  def junior?
    !senior
  end

  def short_name
    first, last = name.split(' ', 2)
    return first if last.nil?

sambostock

React Keys

Consider the difference between these:

function NameList({names}) {
  return (<ul>{names.map((name, index) =>
    <li key={index}>{name}</li>
  )}</ul>);
}

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# frozen_string_literal: true

ruby '2.5.3'

source "https://rubygems.org"

gem 'timecop'
gem 'activesupport'

sambostock

import { Component } from 'react'

export default ClassBasedToggle extends React.Component {
  constructor(props) {
    super(props)
    
    this.state = {
      on: false,
    }