Working With Rails

Morph

Morph allows you to emerge class definitions via calling assignment methods; mix with Hpricot for screen scrapping fun.

Morph example with Hpricot

Here’s example code showing Morph playing with Hpricot:

require 'hpricot'; require 'open-uri'; require 'morph'

class Hubbit
  include Morph  # allows class to morph
end

def initialize name
  doc = Hpricot open("http://github.com/#{name}")
end

(doc/'label').collect do |node|
  label = node.inner_text
  value = node.next_sibling.inner_text.strip
end

morph(label, value)  # morph magic happening here!

def Hubbit name; Hubbit.new name; end

The model emerges from the data. Let’s start by looking up ‘why’:

why = Hubbit 'why'

What new methods do we have?

Hubbit.morph_methods # => ["email", "email=", "name", "name="]

Ah-ha, so we have a name attribute now:

why.name #=> "why the lucky stiff"

Let’s add some of why’s projects:

why.projects = %w[shoes hacketyhack camping hoodwinkd hpricot markaby mousehole parkplace poignant sandbox]

That why’s a productive fellow! Note new accessor methods have been added:

Hubbit.morph_methods # => ["email", "email=", "name", "name=", "projects", "projects="]

Let’s do some more morphing:

dhh = Hubbit 'dhh'

Do we have more methods now?

Hubbit.morph_methods # => ["blog", "blog=", "company", "company=", "email", "email=", "location", "location=" "name", "name=", "projects", "projects="]

So, a new company method has appeared:

dhh.company #=> "37signals"

Morph example from Hash

How about adding a hash of attribute values?

class Order; include Morph; end
order = Order.new
order.morph :drink => 'tea', :spoons_of_sugar => 2, :milk => 'prefer soya thanks'

order.drink  # => "tea" 
order.spoons_of_sugar  # => 2
order.milk  # => "prefer soya thanks"

Morph example hijacking method creation

class VegieFoxes include Morph end

def method_missing symbol, *args
  if (is_writer = symbol.to_s =~ /=$/)
    morph_method_missing(symbol, *args) do |base, attribute|
      create_accessors base, attribute
    end
    send(symbol, *args)
  else
    super
  end
end

private
def create_accessors base, attribute
  base.class_eval "attr_reader :#{attribute}" 
end

base.class_def("#{attribute}=") do |value|
  is_meat = %w[bacon ham].include? value
  value = is_meat ? 'spinach' : value
  instance_variable_set "@#{attribute}".to_sym, value
end

foxes = VegieFoxes.new

foxes.chunky = ‘bacon’ foxes.inspect # => #<vegiefoxes>

foxes.chunky = ‘cheese’ puts foxes.inspect # => #<vegiefoxes>

foxes.pet = ‘ham’ foxes.inspect # => #<vegiefoxes>

Last bits

See examples/ directory for some example code. See LICENSE for the terms of this software.

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NOTE: This description has been extracted from the Plugin README and so the formatting may need updating to make browser friendly