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Making Little Classes out of Big Ones

Hashrocket Lunch n' Learn #1 with Avdi Grimm: Making Little Classes out of Big Ones

A look at the pros and cons of four different techniques for breaking a too-big class into smaller pieces.

CSS: Emulate linear gradients with inset box shadows

Why is this useful?

  • You can have a background image on the same element, overlaying it with a transparent gradient.
  • Since you are probably using gradients to give an element a glossy or three-dimensional feel, box shadows work much better for this. This is because linear gradients always stretch to the full size of the element (which can grow with user input), while a natural shine or shadow only highlights a fixed size on the top or bottom.
  • Browser support for linear gradients is a mess. I avoid using them. In part…
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The (admittedly crazy) goal of this Gem is to be able to format/split all phone numbers in the world.

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Makes a robust determination of a user's timezone through Javascript.

Fixing errors with state_machine when excluding states

This is for you if you get the following strange error from the state_machine gem:

undefined method `-' for #<StateMachine::BlacklistMatcher:0x124769b0>

You probably did something like this in your state_machine ... do block:

def self.final_states
  [ :foo, :bar ]
transition (all - machine.final_states - [:baz]) => :target_state

Instead, define the source states like this:

def self.final_states
  [ :foo, :bar ]
transition (all - (mach...

How Ruby lets you keep script and data in *one* file

The __END__ keyword tells Ruby where a file ends – but you don't have to stop there. Any text you add after it is accessible via the DATA object.

The attached example file data.rb looks like this:

DATA is a File object to everything in the current file after "END"
Running it with ruby data.rb prints:

DATA is a File object to everything in the current file after "__END__"

Manually requiring your application's models will lead to trouble

In a nutshell:

If you require your Rails models manually, pay attention to the path you use. Unless you have to, don't do it at all.


Consider these classes:

# app/models/user.rb

class User < ActiveRecord::Base
  validate :magic

  def magic
    errors.add_to_base('failed') if bad_things?
# app/models/foo.rb

require 'user'

class Foo
  # something happens here

Now, when your environment is booted, Rails will automatically load your models, like User

CSS: Emulate borders with inset box shadows

When is this useful?

  • When both parent and child elements have borders, with this technique you don't get two borders (which looks ugly). This is because child elements are rendered over inset box shadows, not inside inset box shadows.
  • You want more than one border on the same element. You can have as many inset box shadows on the same element as you like, e.g. allowing you to make a picture-frame-like border.


Remember the attribute list of box-shadow is x-offset, y-offset, blur radius, shadow r…

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7 Ways to Decompose Fat ActiveRecord Models - Code Climate Blog

“Fat models” cause maintenance issues in large apps. Only incrementally better than cluttering controllers with domain logic, they usually represent a failure to apply the Single Responsibility Principle (SRP). “Anything related to what a user does” is not a single responsibility.

Early on, SRP is easier to apply. ActiveRecord classes handle persistence, associations and not much else. But bit-by-bit, they grow. Objects that are inherently responsible for persistence become the de facto owner of all business logic as well. And a year or tw…

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Richard Powell presents a collection of CSS styling advice that's mainly taken from SMACSS. Here's my favorites.

#Do not use ID's in CSS Selectors
It is never safe to assume there will only ever be one of something on a page so do not use ID's for CSS. Id's are much better used as javascript hooks so use them for this instead.

.list {…} instead of #list {…}

#Animate an interface using classes not inline styles
Inline styles added by javascript are harder to update and maintain, prefer to add classes using ja…

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Turbolinks makes following links in your web application faster. Instead of letting the browser recompile the JavaScript and CSS between each page change, it keeps the current page instance alive and replaces only the body and the title in the head.

This is similar to pjax, but instead of worrying about what element on the page to replace, and tailoring the server-side response to fit, we replace the entire body. This means that you get the bulk of the speed benefits from pjax (no recompiling of the JavaScript or CSS) without having to tail…

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Creating a Grid for Product View for a eCommerce Site

Randy Hoyt is presenting a way to display something (e.g. products) in a grid. It's responsive, too!

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Show failing specs instantly. Show passing spec as green dots as usual.


# spec/spec.opts (.rspec for rspec 2)
--require rspec/instafail
--format RSpec::Instafail

Automatically strip all string fields of an ActiveRecord

If your application has forms to edit string fields, you probably want to strip the entered values (remove whitespace from beginning and end). The reason is that your users will copy + paste values from unholy places (websites, Microsoft Office) and end up having trailing whitespace in most of their records.

Because browsers ignore whitespace, no one will usually notice this until you get the weirdest bug reports (e.g. two seemingly equal records are not, or multiple records for "unique" values).

Use the attached trait in your model to hav…

RSpec: Change the type of a spec regardless of the folder it lives in

In a Rails application, *_spec.rb files get special treatment depending on the file's directory. E.g. when you put a spec in spec/controllers your examples will have some magic context like controller, post or get that appears out of nowhere.

If you want that magic context for a spec in another folder, use the :type option:

describe CakesController, :type => :controller do
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Takes a screenshot when you call it, or when a test fails.

Literally 101 Ruby tricks

The linked slidedeck holds many tips, of which I list the most interesting to me below


The __END__ keyword tells Ruby where a file ends – but you don't have to stop there. Any text you add after it is accessible via the DATA object.

Running the attached example file data.rb prints:

DATA is a File object to everything in the current file after "__END__"

No braces needed for 'special variables'

@instance, @@class, $global = [ 'instance', 'class', 'global' ]
puts "#@instance, #@@class, #$global" ...

Rspec_spinner or cucumber_spinner get into an infinite loop

Chances are, something in your project uses the mathn library, which is known to cause infinite loops when rendering the progress bar. If so, this will probably fix it.

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