ryanb

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

ryanb

class TasksController < ApplicationController
  def update
    tracker = TaskTracker.new(@task)
    if @task.update_attributes(params[:task])
      TaskPusher.new(tracker, socket_id).push_changes
      TaskMailSender.new(tracker, current_user).deliver_email
      # success response
    else
      # failure respond
    end

jeremy

We've seen lots of Ruby feature requests about converting an Enumerable to a Hash: to_h, map_hash, map_to, each_with_hash, etc. Let's look at one common, simple case of this.

Building a key/value mapping from a collection of keys is awkward. We commonly see Hash[*collection.map { |element| [element, calculate(element)] }] or collection.each_with_object({}) { |element, hash| hash[element] = calculate(element) }. Both are verbose. They require boilerplate code that's not relevant to the programmer's intent: to associate an enumerable of keys with calculated values.

Ruby has the idea of an association already: a key and value paired together. It's used by Array#assoc to look up a value from a list of pairs and by Hash#assoc to return a key/value pair. Building up a mapping of key/value pairs is associating keys with values.

So! Consider Enumerable#associate which builds a mapping by associating keys with values:

# Associate filenames with URLs. Before:

mike-burns

class User < Params.over(:first_name, :last_name)
  def info
    "I am a user: #{@first_name} #{@last_name}"
  end
end

class Admin < User.params(:awesomeness_level)
  def info
    "I am a level #{@awesomeness_level} admin: #{@first_name} #{@last_name}"
  end

mejibyte

http://www.stanford.edu/~liszt90/acm/

peterjmit

#!/bin/bash
# REQUIRES SUDO
# Benchmark runner

repeats=20
output_file='benchmark_results.csv'
command_to_run='echo 1'

run_tests() {
    # --------------------------------------------------------------------------

nikcub

In August 2007 a hacker found a way to expose the PHP source code on facebook.com. He retrieved two files and then emailed them to me, and I wrote about the issue:

http://techcrunch.com/2007/08/11/facebook-source-code-leaked/

It became a big deal:

http://www.techmeme.com/070812/p1#a070812p1

The two files are index.php (the homepage) and search.php (the search page)

ryanb

module Abilities
  def self.ability_for(user)
    if user.admin?
      AdminAbility.new(user)
    else user
      MemberAbility.new(user)
    else
      GuestAbility.new
    end
  end

josevalim

Sinatra like routes in Rails controllers

A proof of concept of having Sinatra like routes inside your controllers.

How to use

Since the router is gone, feel free to remove config/routes.rb. Then add the file below to lib/action_controller/inline_routes.rb inside your app.

mislav

# Public: Implementation of "Strike a match" algorithm for calculating
# similarity between strings.
#
# http://www.catalysoft.com/articles/StrikeAMatch.html
#
# Examples
#
#   checker = StringSimilarityChecker.new('Quick brown fox')
#
#   checker =~ 'quick brown ox'                  #=> true