dojo4 quiz #2

question_1.js

// QUESTION
// write a javascript class, called 'Foo', with a class method 'bar' and an
// instance method 'bar'

var Foo = function Foo(){
  console.log('new Foo instance');
};

Foo.bar = function(){
  console.log('Foo::bar');
}

Foo.prototype.bar = function(){
  console.log('Foo#bar');
}

Foo.bar() // => "Foo::bar"

var baz = new Foo;
baz.bar() // => "Foo#bar"

question_2.rb

=begin
QUESTION
write a ruby class, called 'Foo', and a mixin, 'Bar', that adds a
*class_method* 'baz' and an *instance_method* 'baz'
=end

module Bar
  def self.included( klass )
    klass.extend ClassMethods
    klass.include InstanceMethods
  end

  module ClassMethods
    def baz
      p "class baz"
    end
  end

  module InstanceMethods
    def baz
      p "instance baz"
    end
  end
end

class Foo
  include Bar
end

Foo.baz # => "class baz"
Foo.new.baz # => "instance baz"

question_3.txt

QUESTION
what's wrong with this code?

=> buffer.match( /^foo.*bar/ )

Answer :: The regex will greedy match on the '.*' and never hit the 'bar' at the end

question_4.rb

# QUESTION
# what's wrong with this code?

class Farm
  include Mongoid::Document

  before_save do |farm|
    farm.ensure_no_blank_comments!
  end

  def ensure_no_blank_comments!
    errors.add('teh comments are fubar') if
      comments.any?{|comment| comment.content.blank?}
  end

  class Comment
    embedded_in :farm
    field :content, String
  end

  embeds_many :comments
end

farm = Farm.find(id)
params = { :content => nil }
comment = farm.comments.build(params)
comment.save!

=begin
* Mongoid does not automatically respect nested classes for embedded documents
* The Comment class is not including Mongoid::Document
* The before save check for no blank comments is on the Farm and is not
  automatically triggered when saving an embedded object. Instead, after adding a
  comment with empty content, the Farm object itself will fail to save
=end

alll great save #3. it does match, because it's greedy, but it will backtrack. this gives exponentially bad performance on strings like 'foo (long buffer ) b (long buffer ) ba (long buffer ) ba (long buffer ) b (long buffer) bar'. best summary link i could find before 1st cofee: http://www.codinghorror.com/blog/2006/01/regex-performance.html

Thanks for the link!