Dissecting Ruby with Ruby

Dissecting
Ruby with
Ruby
@schneems

View Slide

@schneems

View Slide

Schnauser

View Slide

View Slide

That man is
married to
Ruby, so to
speak

View Slide

Ruby
Me

View Slide

Python <3 ?

View Slide

Hans
Peter
Von
Wolfe (the 5th)

View Slide

Sextant
Gem

View Slide

Wicked
‘
‘
Gem

View Slide

Triage
Code
codetriage.com

View Slide

View Slide

Adjunct
Professor

View Slide

Good News
Everyone!
schneems.com/ut-rails

View Slide

View Slide

We optimize
developer
happiness

View Slide

Git
Push:
Deploy

View Slide

Ruby
Task
Force

View Slide

Ruby
Task
Force
Member

View Slide

Co-worker

View Slide

Eat
Naan
Talk
Ruby

View Slide

Warning:
I have
Naan
Jokes

View Slide

Some of
them fall
a bit “flat”

View Slide

Close your
Laptops

View Slide

Unless you’re
commenting
on rails/rails
issues

View Slide

We’ve all
been there

View Slide

That
comment is
no longer
valid
“

View Slide

I have no
Idea how it
works, it
just does.
“

View Slide

Docs? Just
look at the
source code
“

View Slide

Get in
Get Info
Get Around

View Slide

Get in

View Slide

$ bundle open wicked

View Slide

Set Editor

View Slide

~/.bashrc
export EDITOR="mvim"

View Slide

~/.bashrc
export EDITOR="subl -w"

View Slide

$
echo $EDITOR
subl -w

View Slide

Get Info
Out

View Slide

Forget
Fancy
Debuggers

View Slide

All you need
is “puts”

View Slide

Tracer Round

View Slide

puts “=================”
Tracer Round

View Slide

Find the
output

View Slide

puts “=================”
Tracer Round

View Slide

puts “=================”
Tracer Round
Do you see it?

View Slide

How about
now?

View Slide

A note on
Notation

View Slide

String.new
Class/Module

View Slide

String.new
Method

View Slide

String.new
class
method

View Slide

Kernel#puts
Not class
method

View Slide

Caution!

View Slide

Nil

View Slide

Nil
Null

View Slide

Nil
Null
Naan

View Slide

Obi-Naan
Kenobi

View Slide

Who uses
Ruby 2.0?

View Slide

Who uses
Ruby 1.9.3?

View Slide

Who uses
Ruby 1.8.7?

View Slide

Ruby 1.8.7
is End of
Life-d in
days

View Slide

try 2.0.0 or
JRuby on
heroku

View Slide

Get Around

View Slide

Let’s look
at Ruby

View Slide

Where is
this method
used?
Problem:

View Slide

Solution:
Kernel#caller

View Slide

www.
ruby-doc
.org

View Slide

Wat?

View Slide

Kernel#caller
gives you the
back trace

View Slide

def self.order_by_issue_count
puts caller.inspect
self.order("issues_count DESC")
end

View Slide

[
"~/projects/triage/app/controllers/pages_controller.rb:6:in `index'",
"ruby/gems/actionpack-3.2.12/lib/action_controller/metal/implicit_render.rb:4:in
"ruby/gems/actionpack-3.2.12/lib/abstract_controller/base.rb:167:in `process_act
"ruby/gems/actionpack-3.2.12/lib/action_controller/metal/rendering.rb:10:in `proc
"ruby/gems/actionpack-3.2.12/lib/abstract_controller/callbacks.rb:18:in `block i
"ruby/gems/activesupport-3.2.12/lib/active_support/callbacks.rb:414:in `_run__37
"ruby/gems/activesupport-3.2.12/lib/active_support/callbacks.rb:405:in `__run_ca
"ruby/gems/activesupport-3.2.12/lib/active_support/callbacks.rb:385:in `_run_pro
"ruby/gems/activesupport-3.2.12/lib/active_support/callbacks.rb:81:in `run_callb
"ruby/gems/actionpack-3.2.12/lib/abstract_controller/callbacks.rb:17:in `process
"ruby/gems/actionpack-3.2.12/lib/action_controller/metal/rescue.rb:29:in `proces
"ruby/gems/actionpack-3.2.12/lib/action_controller/metal/instrumentation.rb:30:i
"ruby/gems/activesupport-3.2.12/lib/active_support/notifications.rb:123:in `bloc
"ruby/gems/activesupport-3.2.12/lib/active_support/notifications/instrumenter.rb
"ruby/gems/activesupport-3.2.12/lib/active_support/notifications.rb:123:in `inst
File

View Slide

[
Line Number

View Slide

[
Method Name

View Slide

Use
Kernel#caller

View Slide

Where is
this method
defined?
Problem:

View Slide

Introducing
My favorite
super secret
class

View Slide

Method

View Slide

Object#method

View Slide

> m = "hello world".method(:upcase)
=> #

View Slide

=> #
> m.class
=> Method

View Slide

=> #
> m.class
=> Method
> m.call
=> "HELLO WORLD"

View Slide

Where is
this method
defined?
Problem: (recap)

View Slide

Solution:
Method#source_location

View Slide

$ cat app/models/user.rb
class User < ActiveRecord::Base
has_many :repo_subscriptions, dependent: :destroy
has_many :repos, :through => :repo_subscriptions
scope :public, where("private is not true")
alias_attribute :token, :github_access_token
def self.random
order("RANDOM()")
end
#...

View Slide

$ rails c
User.last.method(:github_url).source_location

View Slide

$ rails c
=>["~/projects/triage/app/models/user.rb", 93]

View Slide

$ rails c
File

View Slide

$ rails c
Line Number

View Slide

Let’s see
something
real

View Slide

link_to in (rails)
email templates
needs a host set,
but fails if you
include http://
Problem:

View Slide

Fails
config.action_mailer.default_url_options = {
host: 'http://example.com' }
http://http://example.com

View Slide

Works
config.action_mailer.default_url_options = {
host: 'example.com' }
http://example.com

View Slide

let’s remove the
http://
automatically,
but how?
Problem:

View Slide

How does that
option get used?

View Slide

<% puts method(:link_to).source_location %>

View Slide

<% puts method(:link_to).source_location %>
[“ruby/gems/actionpack-3.2.12/lib/action_view/helpers/
url_helper.rb”
231]

View Slide

$ bundle open
$ bundle open actionpack

View Slide

def link_to(*args, &block)
if block_given?
options = args.first || {}
html_options = args.second
link_to(capture(&block), options, html_options)
else
name = args[0]
options = args[1] || {}
html_options = args[2]
html_options = convert_options_to_data_attributes(options, html_options
url = url_for(options)
href = html_options['href']
tag_options = tag_options(html_options)
href_attr = "href=\"#{ERB::Util.html_escape(url)}\"" unless href
"#{ERB::Util.html_escape(name || url)}end
end
{

View Slide

Enhance

View Slide

name = args[0]
html_options = convert_options_to_data_attributes(opt
href_attr = "href=\"#{ERB::Util.html_escape(url)}\""
"#{ERB::Util.html_escap

View Slide

Which
url_for?

View Slide

View Slide

13 matches
12 Files

View Slide

Method#
source_location
to the rescue

View Slide

name = args[0]
html_options = convert_options_to_data_attributes(opt
puts “==============================”
puts method(:url_for).source_location

View Slide

puts “==============================”
puts method(:url_for).source_location
=>
[“actionpack-3.2.12/
lib/
action_view/helpers/url_helper.rb”,
100]

View Slide

def url_for(options = {})
options ||= {}
case options
when String
options
when Hash
options = options.symbolize_keys.reverse_merge!(:
super
when :back
controller.request.env["HTTP_REFERER"] || 'javasc
else
polymorphic_path(options)
end
end

View Slide

options ||= {}
case options
when String
options
when Hash
puts "==========================="
puts self.class.ancestors
super
when :back
else
end
end

View Slide

Module#ancestors

View Slide

“foo”.class.ancestors
=> [String,
Comparable,
Object,
Kernel, BasicObject]

View Slide

options ||= {}
case options
when String
options
when Hash
puts "==========================="
super
when :back
else
end
end

View Slide

puts "==========================="
[#, ##, ActionMailer::MailHelper
ActionDispatch::Routing::RouteSet::MountedHelpers,
#, ActionDispatch::Routing:
ActionView::Base, Devise::OmniAuth::UrlHelpers, Devi
WillPaginate::ActionView, WillPaginate::ViewHelpers,
ActionView::Helpers, ActionView::Helpers::Translatio
ActionView::Helpers::RecordTagHelper, ActionControll
ActionView::Helpers::OutputSafetyHelper, ActionView:
ActionView::Helpers::JavaScriptHelper, ActionView::H
ActionView::Helpers::FormHelper, ActionView::Helpers
ActionView::Helpers::DebugHelper, ActionView::Helper
ActionView::Helpers::ControllerHelper, ActionView::H
ActionView::Helpers::AtomFeedHelper, ActionView::Hel

View Slide

View Slide

Too much
Ruby?

View Slide

Solution:
Moar Ruby

View Slide

Module#method_defined?

View Slide

"foo".class.method_defined?(:upcase)
=> true

View Slide

"foo".class.method_defined?(:upcase)
=> true
99.class.method_defined?(:upcase)
=> false

View Slide

Module#instance_method

View Slide

User.new.method(:github_url).source_location
User.instance_method(:github_url).source_location
Module#instance_method

View Slide

What were we
doing?

View Slide

options ||= {}
case options
when String
options
when Hash
puts "==========================="
super
when :back
else
end
end

View Slide

Right

View Slide

options ||= {}
case options
when String
options
when Hash
options = options.symbolize_keys.reverse_merge!(:only
puts "==========================="
self.class.ancestors.each do |klass|
next unless klass.method_defined?(:url_for)
puts klass.instance_method(:url_for).source_locatio
end
super
when :back
controller.request.env["HTTP_REFERER"] || 'javascript
else

View Slide

self.class.ancestors.each do |klass|
next unless klass.method_defined?(:url_for)
puts klass.instance_method(:url_for).source_location
end
======================
actionpack-3.2.12/lib/action_view/helpers/url_helper.rb
100
100
100
actionpack-3.2.12/lib/action_dispatch/routing/url_for.rb
143

View Slide

======================
100
100
100
143
One of these
things is not like
the others

View Slide

======================
100
100
100
143
Nope

View Slide

======================
100
100
100
143
Yeah!

View Slide

Almost Done
(kinda)

View Slide

Quick
Break:

View Slide

View Slide

Back to your
regularly
scheduled
broadcast

View Slide

Verify Caller
def url_for(options = nil)
puts "==========================="
puts caller.inspect
case options
when String
options
when nil, Hash
_routes.url_for((options || {}).symbolize_keys.rev
else
polymorphic_url(options)
end
end

View Slide

It checks out
============================
[“actionpack-3.2.12/
lib/
action_view/
helpers/
url_helper.rb:112:in `url_for'",
# ...

View Slide

Follow the
Source
def url_for(options = nil)
case options
when String
options
when nil, Hash
puts "==========================="
puts _routes.method(:url_for).source_location
_routes.url_for((options || {}).symbolize_keys.rev
else
polymorphic_url(options)
end
end

View Slide

action_dispatch/routing/route_set.rb:572
def url_for(options)
finalize!
options = (options || {}).reverse_merge!(default_url_options)
handle_positional_args(options)
user, password = extract_authentication(options)
path_segments = options.delete(:_path_segments)
script_name = options.delete(:script_name)
path = (script_name.blank? ? _generate_prefix(options) : script_name.chomp('/')
path_options = options.except(*RESERVED_OPTIONS)
path_options = yield(path_options) if block_given?
path_addition, params = generate(path_options, path_segments || {})
path << path_addition
params.merge!(options[:params] || {})
ActionDispatch::Http::URL.url_for(options.merge!({
:path => path,
:params => params,
:user => user,
:password => password
}))
end

View Slide

Dissecting Ruby with Ruby

Dissecting Ruby with Ruby

Richard Schneeman

More Decks by Richard Schneeman

Other Decks in Programming

Featured

Transcript