Preferences.rb

#
#  Preferences.rb
#  gisteditor
#
#  Created by Greg Borenstein on 6/20/09.
#  Copyright (c) 2009 __MyCompanyName__. All rights reserved.
#

# require '/Users/greg/code/rubycocoa-prefs/lib/abstract_preferences.rb'

require 'singleton'

class NSUserDefaults
  def [](str)
    self.objectForKey(str)
  end
  
  def []=(str, obj)
    self.setObject(obj, forKey:str)
  end
end

class Preferences
  include Singleton
  
  # Save any unsaved changes to disk.
  def save
    Preferences.user_defaults.synchronize
  end
  
  class << self
    # A shortcut method for access to <tt>NSUserDefaults.standardUserDefaults</tt>.
    def user_defaults
      NSUserDefaults.standardUserDefaults
    end
    
    # A hash of all default values for the user defaults
    def default_values
      @default_values ||= {}
    end
    
    # Registers the default values with NSUserDefaults.standardUserDefaults
    # Call this after all your Preferences code has been loaded, for instance
    # in <tt>awakeFromNib</tt> of your ApplicationController.
    def register_default_values!
      user_defaults.registerDefaults(default_values)
    end
  end
  
  class Namespace
    include Singleton
    
    class << self
      # Defines a reader method for the Namespace subclass on the Preferences instance.
      #
      # Defines a class <tt>Preferences::Keyword</tt> and <tt>preferences.keyword</tt>:
      #
      #   class Preferences
      #     class Keyword < Namespace
      #       defaults_accessor :an_option, true
      #     end
      #   end
      def inherited(klass)
        super
        method = klass.name.split('::').last.scan(/[A-Z][a-z]*/).map { |x| x.downcase }.join('_')
        Preferences.class_eval "def #{method}; #{klass.name}.instance end", __FILE__, __LINE__
      end
      
      # The key in the preferences that represents the section class.
      #
      #   Preferences::General.section_defaults_key # => "Preferences.General"
      def section_defaults_key
        @section_defaults_key ||= name.gsub('::', '.')
      end
      
      # Defines a reader and writer method for a user defaults key for this section.
      #
      # If the preference is a boolean value, inflected from the default value,
      # a query method is also defined.
      #
      #   # Defines #confirm_quit, #confirm_quit=, and #confirm_quit? It's default value is <tt>true</tt>.
      #   defaults_accessor :confirm_quit, true
      def defaults_accessor(name, default_value)
        key_path = "#{section_defaults_key}.#{name}"
        Preferences.default_values[key_path] = default_value
        
        class_eval do
          define_method(name) do
            Preferences.user_defaults[key_path]
          end
          
          define_method("#{name}=") do |value|
            Preferences.user_defaults[key_path] = value
          end
          
          if default_value == true || default_value == false
            alias_method "#{name}?", name
          end
        end
        
        key_path
      end
      
      # Besides defining a reader and writer method via defaults_accessor,
      # it also defines a reader method which returns an array of strings
      # wrapped in KVO compatible string wrappers.
      #
      # The name of the wrapper class is defined by <tt>wrapper_class_name</tt>
      # and can be used as the `Class Name' of a NSArrayController.
      # The wrapper exposes `string' as a KVC accessor to which a NSTableColumn can be bound.
      #
      #   # Defines #highlight_words, #highlight_words=, and #highlight_words_wrapped
      #   string_array_defaults_accessor :highlight_words, [], 'HighlightWordWrapper'
      def string_array_defaults_accessor(name, default_value, wrapper_class_name)
        wrapper = eval("class ::#{wrapper_class_name} < StringArrayWrapper; self end")
        wrapper.key_path = defaults_accessor(name, default_value)
        
        class_eval do
          define_method("#{name}_wrapped") do
            ary = []
            send(name).each_with_index { |string, index| ary << wrapper.alloc.initWithString_index(string, index) }
            ary
          end
        end
      end
    end
    
    # Register an observer for a key.
    #
    # Include the <tt>Preferences::KVOCallbackHelper</tt> module in your class
    # to get rubyish callback handling, instead of handling it yourself by defining
    # the observeValueForKeyPath_ofObject_change_context method.
    #
    #   class PreferencesController < OSX::NSWindowController
    #     include Preferences::KVOCallbackHelper
    #
    #     def init
    #       if super_init
    #         preferences.keyword.observe(:highlight_words, self)
    #         self
    #       end
    #     end
    #
    #     def highlight_words_changed(new_value)
    #       # Do stuff because a new value has been set.
    #     end
    #   end
    def observe(name, observer)
      key_path = "values.#{self.class.section_defaults_key}.#{name}"
      NSUserDefaultsController.sharedUserDefaultsController.addObserver(observer,
        forKeyPath:key_path, options:NSKeyValueObservingOptionNew, context:nil
      )
    end
  end
  
  class StringArrayWrapper < NSObject
    class << self
      attr_accessor :key_path
      
      def array
        Preferences.user_defaults[key_path]
      end
      
      def array=(array)
        Preferences.user_defaults[key_path] = array
      end
      
      def destroy(klass, new_wrappers)
        # Set the new correct indices on the remaining wrappers
        new_wrappers.each_with_index do |wrapper, new_index|
          wrapper.index = new_index
        end
        
        # Assign the new result array of strings
        klass.array = new_wrappers.map { |wrapper| wrapper.string }
      end
    end
    
    attr_accessor :string
    attr_accessor :index
    
    def initWithString(string, index:index)
      if init
        @string, @index = string, index
        self
      end
    end
    
    def array
      self.class.array
    end
    
    def array=(array)
      self.class.array = array
    end
    
    def string=(string)
      @string = string
      set_string!
    end
    
    def set_string!
      if @index
        ary = array
        ary[@index] = string
        self.array = ary
      else
        ary = array
        ary << @string
        self.array = ary
        @index = ary.length - 1
      end
    end
    
    def inspect
      "#<#{self.class.name}:#{object_id} string=\"#{@string}\" key_path=\"#{self.class.key_path}\" index=\"#{@index}\">"
    end
  end

  # Extend your class with this module to get access to a few KVC accessor helper methods.
  module AccessorHelpers
    # Defines a kvc_accessor which reads and writes
    # to the specified preferences path (<tt>path_to_eval_to_object</tt>).
    #
    # This is useful for binding, for instance, UI elements
    # to an array in the NSUserDefaults which is normally immutable.
    #
    #   class PreferencesController < OSX::NSWindowController
    #     defaults_kvc_accessor :an_array_of_dictionaries, 'preferences.keyword.url_mappings'
    #   end
    #
    # Binding a NSArrayController to File's Owner with key path: <tt>an_array_of_dictionaries</tt>,
    # will perform the following read/write actions on the NSUserDefaults:
    #
    #   preferences_controller.valueForKey('an_array_of_dictionaries') # => [{'key' => 'value 1'}, {'key' => 'value 2'}]
    #   preferences_controller.setValueForKey([{'key' => 'value 1'}], 'an_array_of_dictionaries')
    #   preferences_controller.valueForKey('an_array_of_dictionaries') # => [{'key' => 'value 1'}]
    def defaults_kvc_accessor(name, path_to_eval_to_object)
      kvc_accessor(name)
      
      class_eval %{
        def #{name}
          @#{name} ||= #{path_to_eval_to_object}
        end
        
        def #{name}=(new_defaults)
          #{path_to_eval_to_object} = @#{name} = new_defaults
        end
      }, __FILE__, __LINE__
    end
    
    # Defines read and write KVC accessors like defaults_kvc_accessor does,
    # but is used specifically for defaults defined with Namespace#string_array_defaults_accessor.
    #
    #   class PreferencesController < OSX::NSWindowController
    #     defualts_string_array_kvc_accessor :an_array_of_strings, 'preferences.keyword.highlight_words'
    #   end
    #
    # See Namespace#string_array_defaults_accessor for more info.
    def defualts_string_array_kvc_accessor(name, path_to_eval_to_object)
      defaults_kvc_accessor(name, "#{path_to_eval_to_object}_wrapped")
      
      class_eval %{
        def #{name}=(new_wrappers)
          if new_wrappers.length < #{name}.length
            Preferences::StringArrayWrapper.destroy(#{name}.first.class, new_wrappers)
          end
          @#{name} = new_wrappers
        end
      }, __FILE__, __LINE__
    end
  end
  
end

module Kernel
  # A shortcut method for easy access anywhere to the shared user defaults.
  def preferences
    Preferences.instance
  end
end

class Preferences
  class User < Namespace
    defaults_accessor :login, "YOUR LOGIN HERE"
    defaults_accessor :token, "YOUR TOKEN HERE"
  end
  
  # Register the default values with NSUserDefaults.standardUserDefaults.
  register_default_values!
end