[英]How to DRY this code in Ruby
我有以下代码来表示Ruby中的不同Value Object。 不同类之间唯一发生变化的是INITIALIZATION_ATTRIBUTES数组,该数组表示值对象的属性列表。 我找不到干燥该代码的方法。 我尝试使用Module并访问包含的类的Constants,但是遇到了此处描述的怪异的Constant查找行为。 本质上,对模块代码进行多次评估,并解释最后评估的类的常量,并将其值应用于所有值对象类。
还有更好的选择吗? 我也尝试过使用基类,但是无法使其正常工作。
module Values
class MaintenanceRegimeSerializer
INITIALIZATION_ATTRIBUTES = [:distance_between_services, :months_between_services]
def self.load(json)
json ||= '{}'
hash = JSON.parse json, symbolize_names: true
self.new(*INITIALIZATION_ATTRIBUTES.map {|key| hash[key]})
end
def self.dump(obj)
unless obj.is_a?(self)
raise ::ActiveRecord::SerializationTypeMismatch,
"Attribute was supposed to be a #{self}, but was a #{obj.class}. -- #{obj.inspect}"
end
obj.to_json
end
attr_reader *INITIALIZATION_ATTRIBUTES
define_method :initialize do |*args|
raise ArgumentError unless INITIALIZATION_ATTRIBUTES.length == args.length
INITIALIZATION_ATTRIBUTES.each_with_index do |attribute, index|
instance_variable_set "@#{attribute}", args[index]
end
end
end
end
这可以通过分层两个模块来完成。 外部模块将提供初始化内部模块的功能。 因为使用的类属性对于每个包含类都是唯一的,所以一个包含类的属性不能与另一个包含类的属性冲突。
module Values
module MaintenanceRegimeSerializer
extend ActiveSupport::Concern
class_methods do
def acts_as_maintenance_regime_serializer(attributes)
# include the inner module
# thereby adding the required methods and class attributes
include JsonMethods
# set the class variables made available by including the inner module
self.serializer_attributes = attributes
end
end
module JsonMethods
extend ActiveSupport::Concern
included do
class_attribute :serializer_attributes
def initialize(*args)
raise ArgumentError unless self.class.serializer_attributes.length == args.length
self.class.serializer_attributes.each_with_index do |attribute, index|
instance_variable_set "@#{attribute}", args[index]
end
end
end
class_methods do
def load(json)
json ||= '{}'
hash = JSON.parse json, symbolize_names: true
new(*serializer_attributes.map {|key| hash[key]})
end
def dump(obj)
unless obj.is_a?(self)
raise ::ActiveRecord::SerializationTypeMismatch,
"Attribute was supposed to be a #{self}, but was a #{obj.class}. -- #{obj.inspect}"
end
obj.to_json
end
end
end
end
end
# in the including class
class SomeClass
# This might also be put into an initializer patching ActiveRecord::Base
# to avoid having to call this in every class desiring the regime serializer functionalit
include Values::MaintenanceRegimeSerializer
acts_as_maintenance_regime_serializer([:distance_between_services,
:months_between_services])
end
# in another including class
class SomeOtherClass
include Values::MaintenanceRegimeSerializer
acts_as_maintenance_regime_serializer([:foo,
:bar])
end
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