----

-layout: default

-title: Syntax Highlighting Debug

----

-<div class="code_window">

-<em>Ruby</em>

-{% highlight ruby %}

-def rebuild_site(relative)

- puts ">>> Change Detected to: #{relative} <<<"

- IO.popen('rake generate') do |io|

- print(io.readpartial(512)) until io.eof?

- end

- puts '>>> Update Complete <<<'

-end

-{% endhighlight %}

-</div>

-

-So that's a small example. What about a big one?

-

-<div class="code_window">

-<em>Ruby</em>

-{% highlight ruby %}

-require 'active_support/core_ext/array'

-require 'active_support/core_ext/hash/except'

-require 'active_support/core_ext/object/metaclass'

-

-module ActiveRecord

- module NamedScope

- extend ActiveSupport::Concern

-

- # All subclasses of ActiveRecord::Base have one named scope:

- # * <tt>scoped</tt> - which allows for the creation of anonymous \scopes, on the fly: <tt>Shirt.scoped(:conditions => {:color => 'red'}).scoped(:include => :washing_instructions)</tt>

- #

- # These anonymous \scopes tend to be useful when procedurally generating complex queries, where passing

- # intermediate values (scopes) around as first-class objects is convenient.

- #

- # You can define a scope that applies to all finders using ActiveRecord::Base.default_scope.

- included do

- named_scope :scoped, lambda { |scope| scope }

- end

-

- module ClassMethods

- def scopes

- read_inheritable_attribute(:scopes) || write_inheritable_attribute(:scopes, {})

- end

-

- # Adds a class method for retrieving and querying objects. A scope represents a narrowing of a database query,

- # such as <tt>:conditions => {:color => :red}, :select => 'shirts.*', :include => :washing_instructions</tt>.

- #

- # class Shirt < ActiveRecord::Base

- # named_scope :red, :conditions => {:color => 'red'}

- # named_scope :dry_clean_only, :joins => :washing_instructions, :conditions => ['washing_instructions.dry_clean_only = ?', true]

- # end

- #

- # The above calls to <tt>named_scope</tt> define class methods Shirt.red and Shirt.dry_clean_only. Shirt.red,

- # in effect, represents the query <tt>Shirt.find(:all, :conditions => {:color => 'red'})</tt>.

- #

- # Unlike <tt>Shirt.find(...)</tt>, however, the object returned by Shirt.red is not an Array; it resembles the association object

- # constructed by a <tt>has_many</tt> declaration. For instance, you can invoke <tt>Shirt.red.find(:first)</tt>, <tt>Shirt.red.count</tt>,

- # <tt>Shirt.red.find(:all, :conditions => {:size => 'small'})</tt>. Also, just

- # as with the association objects, named \scopes act like an Array, implementing Enumerable; <tt>Shirt.red.each(&block)</tt>,

- # <tt>Shirt.red.first</tt>, and <tt>Shirt.red.inject(memo, &block)</tt> all behave as if Shirt.red really was an Array.

- #

- # These named \scopes are composable. For instance, <tt>Shirt.red.dry_clean_only</tt> will produce all shirts that are both red and dry clean only.

- # Nested finds and calculations also work with these compositions: <tt>Shirt.red.dry_clean_only.count</tt> returns the number of garments

- # for which these criteria obtain. Similarly with <tt>Shirt.red.dry_clean_only.average(:thread_count)</tt>.

- #

- # All \scopes are available as class methods on the ActiveRecord::Base descendant upon which the \scopes were defined. But they are also available to

- # <tt>has_many</tt> associations. If,

- #

- # class Person < ActiveRecord::Base

- # has_many :shirts

- # end

- #

- # then <tt>elton.shirts.red.dry_clean_only</tt> will return all of Elton's red, dry clean

- # only shirts.

- #

- # Named \scopes can also be procedural:

- #

- # class Shirt < ActiveRecord::Base

- # named_scope :colored, lambda { |color|

- # { :conditions => { :color => color } }

- # }

- # end

- #

- # In this example, <tt>Shirt.colored('puce')</tt> finds all puce shirts.

- #

- # Named \scopes can also have extensions, just as with <tt>has_many</tt> declarations:

- #

- # class Shirt < ActiveRecord::Base

- # named_scope :red, :conditions => {:color => 'red'} do

- # def dom_id

- # 'red_shirts'

- # end

- # end

- # end

- #

- #

- # For testing complex named \scopes, you can examine the scoping options using the

- # <tt>proxy_options</tt> method on the proxy itself.

- #

- # class Shirt < ActiveRecord::Base

- # named_scope :colored, lambda { |color|

- # { :conditions => { :color => color } }

- # }

- # end

- #

- # expected_options = { :conditions => { :colored => 'red' } }

- # assert_equal expected_options, Shirt.colored('red').proxy_options

- def named_scope(name, options = {}, &block)

- name = name.to_sym

- scopes[name] = lambda do |parent_scope, *args|

- Scope.new(parent_scope, case options

- when Hash

- options

- when Proc

- options.call(*args)

- end, &block)

- end

- metaclass.instance_eval do

- define_method name do |*args|

- scopes[name].call(self, *args)

- end

- end

- end

- end

-

- class Scope

- attr_reader :proxy_scope, :proxy_options, :current_scoped_methods_when_defined

- NON_DELEGATE_METHODS = %w(nil? send object_id class extend find size count sum average maximum minimum paginate first last empty? any? many? respond_to?).to_set

- [].methods.each do |m|

- unless m =~ /^__/ || NON_DELEGATE_METHODS.include?(m.to_s)

- delegate m, :to => :proxy_found

- end

- end

-

- delegate :scopes, :with_scope, :scoped_methods, :to => :proxy_scope

-

- def initialize(proxy_scope, options, &block)

- options ||= {}

- [options[:extend]].flatten.each { |extension| extend extension } if options[:extend]

- extend Module.new(&block) if block_given?

- unless Scope === proxy_scope

- @current_scoped_methods_when_defined = proxy_scope.send(:current_scoped_methods)

- end

- @proxy_scope, @proxy_options = proxy_scope, options.except(:extend)

- end

-

- def reload

- load_found; self

- end

-

- def first(*args)

- if args.first.kind_of?(Integer) || (@found && !args.first.kind_of?(Hash))

- proxy_found.first(*args)

- else

- find(:first, *args)

- end

- end

-

- def last(*args)

- if args.first.kind_of?(Integer) || (@found && !args.first.kind_of?(Hash))

- proxy_found.last(*args)

- else

- find(:last, *args)

- end

- end

-

- def size

- @found ? @found.length : count

- end

-

- def empty?

- @found ? @found.empty? : count.zero?

- end

-

- def respond_to?(method, include_private = false)

- super || @proxy_scope.respond_to?(method, include_private)

- end

-

- def any?

- if block_given?

- proxy_found.any? { |*block_args| yield(*block_args) }

- else

- !empty?

- end

- end

-

- # Returns true if the named scope has more than 1 matching record.

- def many?

- if block_given?

- proxy_found.many? { |*block_args| yield(*block_args) }

- else

- size > 1

- end

- end

-

- protected

- def proxy_found

- @found || load_found

- end

-

- private

- def method_missing(method, *args, &block)

- if scopes.include?(method)

- scopes[method].call(self, *args)

- else

- with_scope({:find => proxy_options, :create => proxy_options[:conditions].is_a?(Hash) ? proxy_options[:conditions] : {}}, :reverse_merge) do

- method = :new if method == :build

- if current_scoped_methods_when_defined && !scoped_methods.include?(current_scoped_methods_when_defined)

- with_scope current_scoped_methods_when_defined do

- proxy_scope.send(method, *args, &block)

- end

- else

- proxy_scope.send(method, *args, &block)

- end

- end

- end

- end

-

- def load_found

- @found = find(:all)

- end

- end

- end

-end

-{% endhighlight %}

-</div> \ No newline at end of file