harlow

My issues with Modules

In researching topics for RailsCasts I often read code in Rails and other gems. This is a great exercise to do. Not only will you pick up some coding tips, but it can help you better understand what makes code readable.

A common practice to organize code in gems is to divide it into modules. When this is done extensively I find it becomes very difficult to read. Before I explain further, a quick detour on instance_eval.

You can find instance_eval used in many DSLs: from routes to state machines. Here's an example from Thinking Sphinx.

class Article < ActiveRecord::Base

harlow

{
  "id": "custom_id", // the webhook_id passed in the lookup params
  "status": 200,
  "type": "company",
  "body": {
    // Company attributes
  }
}

harlow

# Navigating
  visit('/projects')
  visit(post_comments_path(post))

# Clicking links and buttons
  click_link('id-of-link')
  click_link('Link Text')
  click_button('Save')
  click('Link Text') # Click either a link or a button
  click('Button Value')

harlow

#!/usr/bin/env ruby
require 'open-uri'
require 'nokogiri'
require 'json'

class Repo
  def initialize(name)
    @name = name
  end

harlow

Add contributors pull requests to your origin remote

# .git/config
[remote "origin"]
  fetch = +refs/heads/*:refs/remotes/origin/*
  fetch = +refs/pull/*/head:refs/remotes/origin/pr/*
  url = git@github.com:thoughtbot/[repo].git

Fetch and checkout the remote branch. Run bundle to make sure any new dependencies are installed.

harlow

# This will guess the User class
Factory.define :user do
  first_name 'John'
  last_name  'Doe'
  admin false
end

# This will use the User class (Admin would have been guessed)
Factory.define :admin, :class => User do |u|

harlow

def set_cache_control_headers(max_age = 1.second.to_s)
  if request.method == "GET"
    request.session_options[:skip] = true
    response.cache_control[:public] = true
    response.cache_control[:extras] = ['no-cache']
    response.headers['Surrogate-Control'] = "max-age=#{max_age}"
  end
end

harlow

1. Your class can be no longer than 100 lines of code.
2. Your methods can be no longer than five lines of code.
3. You can pass no more than four parameters and you can’t just make it one big hash.
4. When a call comes into your Rails controller, you can only instantiate one object to do whatever it is that needs to be done.

You can break these rules if you can talk your pair into agreeing with you.

harlow

# app/models/customer.rb
class Customer
  attr_reader :id, :country

  def initialize(attrs = {})
    @id = attrs[:id]
    @country = attrs[:country]
  end

  def tax_code

harlow

# coding: utf-8
require 'sinatra'
set server: 'thin', connections: []

get '/' do
  halt erb(:login) unless params[:user]
  erb :chat, locals: { user: params[:user].gsub(/\W/, '') }
end

get '/stream', provides: 'text/event-stream' do