Ruby - 结构和命名参数继承

Question

这个问题完全是关于 Struct 行为的，所以请不要问“为什么在广泛的体育世界中你要那样做？”

此代码不正确，但它应该说明我试图了解的有关 Ruby Structs 的内容:

class Person < Struct.new(:name, :last_name)
end

class ReligiousPerson < Person(:religion)
end

class PoliticalPerson < Person(:political_affiliation)
end

### Main ###

person = Person.new('jackie', 'jack')
pious_person = ReligiousPerson.new('billy', 'bill', 'Zoroastrianism')
political_person = PoliticalPerson.new('frankie', 'frank', 'Connecticut for Lieberman')

如您所见，尝试使用 Structs 定义类继承。但是，当然，当您尝试初始化 ReligiousPerson 或 PoliticalPerson 时，Ruby 会变得脾气暴躁。因此，鉴于此说明性代码，如何使用这种使用 Structs 的类继承来继承命名参数？

Answer 1

您可以定义基于 Person 的新结构:

class Person < Struct.new(:name, :last_name)
end

class ReligiousPerson < Struct.new(*Person.members, :religion)  
end

class PoliticalPerson < Struct.new(*Person.members, :political_affiliation)
end

### Main ###

person = Person.new('jackie', 'jack')
p pious_person = ReligiousPerson.new('billy', 'bill', 'Zoroastrianism')
p political_person = PoliticalPerson.new('frankie', 'frank', 'Connecticut for Lieberman')

结果:

#<struct ReligiousPerson name="billy", last_name="bill", religion="Zoroastrianism">
#<struct PoliticalPerson name="frankie", last_name="frank", political_affiliation="Connecticut for Lieberman">

在发布我的答案后我立即有了一个想法:

class Person < Struct.new(:name, :last_name)
  def self.derived_struct( *args )
    Struct.new(*self.members, *args)
  end
end

class ReligiousPerson < Person.derived_struct(:religion)  
end

class PoliticalPerson < Person.derived_struct(:political_affiliation)
end

### Main ###

person = Person.new('jackie', 'jack')
p pious_person = ReligiousPerson.new('billy', 'bill', 'Zoroastrianism')
p political_person = PoliticalPerson.new('frankie', 'frank', 'Connecticut for Lieberman')

工作正常!

您还可以将#derived_struct 添加到 Struct:

class Struct
  def self.derived_struct( *args )
    Struct.new(*self.members, *args)
  end
end