ruby – 基于一个属性的不区分大小写的equals方法

这是一个非常可怕的方法,它根据代码检查相等性,但不区分大小写

def ==(another_country)
   (code.nil? ? nil : code.downcase) == (another_country.code.nil? ? nil : another_country.code.downcase) unless another_country.nil?
end

你能指出我正确的方向如何写这个更优雅的w / o reliying丑陋的if else结构？

这是我最终使用的解决方案(RSpecs)

# Country model
class Country < ActiveRecord::Base
  attr_accessible :code

  def ==(another_country)
    code.to_s.downcase == another_country.code.to_s.downcase rescue false
  end
end

广泛的测试：

# RSpec
describe Country do
   describe 'equality based solely on Country.code' do
      before do
        @country_code_de = FactoryGirl.build(:country,:code => 'de')
      end

      it 'should be equal if Country.code is equal' do
        other_country_code_de = FactoryGirl.build(:country,:code => 'de')
        @country_code_de.should == other_country_code_de
      end

      it 'should be not equal if Country.code is not equal' do
        country_code_usa = FactoryGirl.build(:country,:code => 'usa')
        @country_code_de.should_not == country_code_usa
      end

      it 'should be case insensitive' do
        country_code_de_uppercase = FactoryGirl.build(:country,:code => 'DE')
        @country_code_de.should == country_code_de_uppercase
      end

      it 'should not rely on id for equality' do
        @country_code_de.id = 0
        country_code_usa = FactoryGirl.build(:country,:code => 'usa',:id => 0)
        @country_code_de.should_not == country_code_usa
      end

      it 'should be not equal if Country.code of one Country is nil' do
        country_code_nil = FactoryGirl.build(:country,:code => nil)
        @country_code_de.should_not == country_code_nil
      end

      it 'should be equal if Country.code for both countries is nil' do
        country_code_nil = FactoryGirl.build(:country,:code => nil)
        other_country_code_nil = FactoryGirl.build(:country,:code => nil)
        country_code_nil.should == other_country_code_nil
      end

      it 'should be not equal if other Country is nil' do
        @country_code_de.should_not == nil
      end

      it 'should be not equal if other object is not a Country' do
        @country_code_de.should_not == 'test'
      end

      it 'should be equal for descendants of Country with same Country.code' do
        class CountryChild < Country
        end
        country_child = CountryChild.new(:code => 'de')
        @country_code_de.should == country_child
      end
    end
end