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93c1f11c0a
The problem: We need to be able to specify configuration in a way that can be inherited to models that include ActiveRecord::Model. So it is no longer sufficient to put 'top level' config on ActiveRecord::Base, but we do want configuration specified on ActiveRecord::Base and descendants to continue to work. So we need something like class_attribute that can be defined on a module but that is inherited when ActiveRecord::Model is included. The solution: added ActiveModel::Configuration module which provides a config_attribute macro. It's a bit specific hence I am not putting this in Active Support or making it a 'public API' at present.
412 lines
14 KiB
Ruby
412 lines
14 KiB
Ruby
require 'active_support/core_ext/hash/keys'
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require 'active_support/core_ext/class/attribute'
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require 'active_support/deprecation'
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module ActiveModel
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class MissingAttributeError < NoMethodError
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end
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# == Active Model Attribute Methods
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#
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# <tt>ActiveModel::AttributeMethods</tt> provides a way to add prefixes and suffixes
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# to your methods as well as handling the creation of Active Record like class methods
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# such as +table_name+.
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#
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# The requirements to implement ActiveModel::AttributeMethods are to:
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#
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# * <tt>include ActiveModel::AttributeMethods</tt> in your object
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# * Call each Attribute Method module method you want to add, such as
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# attribute_method_suffix or attribute_method_prefix
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# * Call <tt>define_attribute_methods</tt> after the other methods are
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# called.
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# * Define the various generic +_attribute+ methods that you have declared
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#
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# A minimal implementation could be:
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#
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# class Person
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# include ActiveModel::AttributeMethods
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#
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# attribute_method_affix :prefix => 'reset_', :suffix => '_to_default!'
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# attribute_method_suffix '_contrived?'
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# attribute_method_prefix 'clear_'
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# define_attribute_methods ['name']
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#
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# attr_accessor :name
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#
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# private
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#
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# def attribute_contrived?(attr)
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# true
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# end
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#
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# def clear_attribute(attr)
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# send("#{attr}=", nil)
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# end
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#
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# def reset_attribute_to_default!(attr)
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# send("#{attr}=", "Default Name")
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# end
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# end
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#
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# Note that whenever you include ActiveModel::AttributeMethods in your class,
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# it requires you to implement an <tt>attributes</tt> method which returns a hash
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# with each attribute name in your model as hash key and the attribute value as
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# hash value.
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#
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# Hash keys must be strings.
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#
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module AttributeMethods
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extend ActiveSupport::Concern
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NAME_COMPILABLE_REGEXP = /\A[a-zA-Z_]\w*[!?=]?\z/
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CALL_COMPILABLE_REGEXP = /\A[a-zA-Z_]\w*[!?]?\z/
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included do
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extend ActiveModel::Configuration
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config_attribute :attribute_method_matchers
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self.attribute_method_matchers = [ClassMethods::AttributeMethodMatcher.new]
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end
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module ClassMethods
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# Declares a method available for all attributes with the given prefix.
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# Uses +method_missing+ and <tt>respond_to?</tt> to rewrite the method.
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#
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# #{prefix}#{attr}(*args, &block)
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#
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# to
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#
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# #{prefix}attribute(#{attr}, *args, &block)
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#
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# An instance method <tt>#{prefix}attribute</tt> must exist and accept
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# at least the +attr+ argument.
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#
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# For example:
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#
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# class Person
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#
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# include ActiveModel::AttributeMethods
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# attr_accessor :name
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# attribute_method_prefix 'clear_'
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# define_attribute_methods [:name]
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#
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# private
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#
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# def clear_attribute(attr)
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# send("#{attr}=", nil)
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# end
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# end
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#
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# person = Person.new
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# person.name = "Bob"
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# person.name # => "Bob"
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# person.clear_name
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# person.name # => nil
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def attribute_method_prefix(*prefixes)
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self.attribute_method_matchers += prefixes.map { |prefix| AttributeMethodMatcher.new :prefix => prefix }
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undefine_attribute_methods
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end
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# Declares a method available for all attributes with the given suffix.
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# Uses +method_missing+ and <tt>respond_to?</tt> to rewrite the method.
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#
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# #{attr}#{suffix}(*args, &block)
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#
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# to
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#
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# attribute#{suffix}(#{attr}, *args, &block)
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#
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# An <tt>attribute#{suffix}</tt> instance method must exist and accept at least
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# the +attr+ argument.
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#
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# For example:
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#
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# class Person
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#
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# include ActiveModel::AttributeMethods
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# attr_accessor :name
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# attribute_method_suffix '_short?'
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# define_attribute_methods [:name]
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#
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# private
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#
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# def attribute_short?(attr)
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# send(attr).length < 5
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# end
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# end
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#
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# person = Person.new
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# person.name = "Bob"
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# person.name # => "Bob"
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# person.name_short? # => true
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def attribute_method_suffix(*suffixes)
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self.attribute_method_matchers += suffixes.map { |suffix| AttributeMethodMatcher.new :suffix => suffix }
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undefine_attribute_methods
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end
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# Declares a method available for all attributes with the given prefix
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# and suffix. Uses +method_missing+ and <tt>respond_to?</tt> to rewrite
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# the method.
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#
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# #{prefix}#{attr}#{suffix}(*args, &block)
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#
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# to
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#
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# #{prefix}attribute#{suffix}(#{attr}, *args, &block)
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#
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# An <tt>#{prefix}attribute#{suffix}</tt> instance method must exist and
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# accept at least the +attr+ argument.
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#
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# For example:
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#
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# class Person
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#
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# include ActiveModel::AttributeMethods
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# attr_accessor :name
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# attribute_method_affix :prefix => 'reset_', :suffix => '_to_default!'
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# define_attribute_methods [:name]
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#
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# private
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#
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# def reset_attribute_to_default!(attr)
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# ...
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# end
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# end
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#
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# person = Person.new
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# person.name # => 'Gem'
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# person.reset_name_to_default!
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# person.name # => 'Gemma'
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def attribute_method_affix(*affixes)
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self.attribute_method_matchers += affixes.map { |affix| AttributeMethodMatcher.new :prefix => affix[:prefix], :suffix => affix[:suffix] }
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undefine_attribute_methods
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end
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def alias_attribute(new_name, old_name)
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attribute_method_matchers.each do |matcher|
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matcher_new = matcher.method_name(new_name).to_s
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matcher_old = matcher.method_name(old_name).to_s
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define_optimized_call self, matcher_new, matcher_old
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end
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end
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# Declares the attributes that should be prefixed and suffixed by
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# ActiveModel::AttributeMethods.
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#
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# To use, pass in an array of attribute names (as strings or symbols),
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# be sure to declare +define_attribute_methods+ after you define any
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# prefix, suffix or affix methods, or they will not hook in.
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#
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# class Person
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#
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# include ActiveModel::AttributeMethods
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# attr_accessor :name, :age, :address
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# attribute_method_prefix 'clear_'
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#
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# # Call to define_attribute_methods must appear after the
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# # attribute_method_prefix, attribute_method_suffix or
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# # attribute_method_affix declares.
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# define_attribute_methods [:name, :age, :address]
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#
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# private
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#
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# def clear_attribute(attr)
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# ...
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# end
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# end
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def define_attribute_methods(attr_names)
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attr_names.each { |attr_name| define_attribute_method(attr_name) }
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end
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def define_attribute_method(attr_name)
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attribute_method_matchers.each do |matcher|
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method_name = matcher.method_name(attr_name)
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unless instance_method_already_implemented?(method_name)
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generate_method = "define_method_#{matcher.method_missing_target}"
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if respond_to?(generate_method)
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send(generate_method, attr_name)
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else
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define_optimized_call generated_attribute_methods, method_name, matcher.method_missing_target, attr_name.to_s
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end
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end
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end
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attribute_method_matchers_cache.clear
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end
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# Removes all the previously dynamically defined methods from the class
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def undefine_attribute_methods
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generated_attribute_methods.module_eval do
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instance_methods.each { |m| undef_method(m) }
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end
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attribute_method_matchers_cache.clear
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end
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# Returns true if the attribute methods defined have been generated.
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def generated_attribute_methods #:nodoc:
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@generated_attribute_methods ||= begin
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mod = Module.new
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include mod
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mod
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end
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end
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protected
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def instance_method_already_implemented?(method_name)
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generated_attribute_methods.method_defined?(method_name)
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end
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private
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# The methods +method_missing+ and +respond_to?+ of this module are
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# invoked often in a typical rails, both of which invoke the method
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# +match_attribute_method?+. The latter method iterates through an
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# array doing regular expression matches, which results in a lot of
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# object creations. Most of the times it returns a +nil+ match. As the
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# match result is always the same given a +method_name+, this cache is
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# used to alleviate the GC, which ultimately also speeds up the app
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# significantly (in our case our test suite finishes 10% faster with
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# this cache).
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def attribute_method_matchers_cache #:nodoc:
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@attribute_method_matchers_cache ||= {}
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end
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def attribute_method_matcher(method_name) #:nodoc:
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if attribute_method_matchers_cache.key?(method_name)
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attribute_method_matchers_cache[method_name]
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else
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# Must try to match prefixes/suffixes first, or else the matcher with no prefix/suffix
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# will match every time.
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matchers = attribute_method_matchers.partition(&:plain?).reverse.flatten(1)
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match = nil
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matchers.detect { |method| match = method.match(method_name) }
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attribute_method_matchers_cache[method_name] = match
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end
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end
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# Define a method `name` in `mod` that dispatches to `send`
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# using the given `extra` args. This fallbacks `define_method`
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# and `send` if the given names cannot be compiled.
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def define_optimized_call(mod, name, send, *extra) #:nodoc:
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if name =~ NAME_COMPILABLE_REGEXP
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defn = "def #{name}(*args)"
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else
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defn = "define_method(:'#{name}') do |*args|"
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end
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extra = (extra.map(&:inspect) << "*args").join(", ")
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if send =~ CALL_COMPILABLE_REGEXP
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target = "#{send}(#{extra})"
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else
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target = "send(:'#{send}', #{extra})"
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end
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mod.module_eval <<-RUBY, __FILE__, __LINE__ + 1
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#{defn}
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#{target}
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end
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RUBY
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end
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class AttributeMethodMatcher
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attr_reader :prefix, :suffix, :method_missing_target
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AttributeMethodMatch = Struct.new(:target, :attr_name, :method_name)
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def initialize(options = {})
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options.symbolize_keys!
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if options[:prefix] == '' || options[:suffix] == ''
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ActiveSupport::Deprecation.warn(
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"Specifying an empty prefix/suffix for an attribute method is no longer " \
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"necessary. If the un-prefixed/suffixed version of the method has not been " \
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"defined when `define_attribute_methods` is called, it will be defined " \
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"automatically."
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)
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end
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@prefix, @suffix = options[:prefix] || '', options[:suffix] || ''
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@regex = /^(#{Regexp.escape(@prefix)})(.+?)(#{Regexp.escape(@suffix)})$/
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@method_missing_target = "#{@prefix}attribute#{@suffix}"
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@method_name = "#{prefix}%s#{suffix}"
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end
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def match(method_name)
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if @regex =~ method_name
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AttributeMethodMatch.new(method_missing_target, $2, method_name)
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else
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nil
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end
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end
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def method_name(attr_name)
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@method_name % attr_name
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end
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def plain?
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prefix.empty? && suffix.empty?
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end
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end
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end
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# Allows access to the object attributes, which are held in the
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# <tt>@attributes</tt> hash, as though they were first-class methods. So a
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# Person class with a name attribute can use Person#name and Person#name=
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# and never directly use the attributes hash -- except for multiple assigns
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# with ActiveRecord#attributes=. A Milestone class can also ask
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# Milestone#completed? to test that the completed attribute is not +nil+
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# or 0.
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#
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# It's also possible to instantiate related objects, so a Client class
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# belonging to the clients table with a +master_id+ foreign key can
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# instantiate master through Client#master.
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def method_missing(method, *args, &block)
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if respond_to_without_attributes?(method, true)
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super
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else
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match = match_attribute_method?(method.to_s)
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match ? attribute_missing(match, *args, &block) : super
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end
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end
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# attribute_missing is like method_missing, but for attributes. When method_missing is
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# called we check to see if there is a matching attribute method. If so, we call
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# attribute_missing to dispatch the attribute. This method can be overloaded to
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# customise the behaviour.
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def attribute_missing(match, *args, &block)
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__send__(match.target, match.attr_name, *args, &block)
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end
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# A Person object with a name attribute can ask <tt>person.respond_to?(:name)</tt>,
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# <tt>person.respond_to?(:name=)</tt>, and <tt>person.respond_to?(:name?)</tt>
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# which will all return +true+.
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alias :respond_to_without_attributes? :respond_to?
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def respond_to?(method, include_private_methods = false)
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if super
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true
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elsif !include_private_methods && super(method, true)
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# If we're here then we haven't found among non-private methods
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# but found among all methods. Which means that the given method is private.
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false
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else
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!match_attribute_method?(method.to_s).nil?
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end
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end
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protected
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def attribute_method?(attr_name)
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attributes.include?(attr_name)
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end
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private
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# Returns a struct representing the matching attribute method.
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# The struct's attributes are prefix, base and suffix.
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def match_attribute_method?(method_name)
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match = self.class.send(:attribute_method_matcher, method_name)
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match && attribute_method?(match.attr_name) ? match : nil
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end
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def missing_attribute(attr_name, stack)
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raise ActiveModel::MissingAttributeError, "missing attribute: #{attr_name}", stack
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end
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end
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end
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