可能有助于代码重构 [英] Possible help in code refactoring

问题描述

Sandi Metz 在 GORUCO 的 SOLID OOPS 概念 中说，Ruby 中 if..else 块的存在可以被认为是一种偏差来自开闭原则.可以使用哪些所有方法来避免不紧急的 if..else 条件?我尝试了以下代码:

Sandi Metz says in SOLID OOPS concepts from GORUCO that presence of if..else blocks in Ruby can be considered to be a deviation from Open-Close Principle. What all methods can be used to avoid not-urgent if..else conditions? I tried the following code:

class Fun
   def park(s=String.new)
      puts s
   end
   def park(i=Fixnum.new)
      i=i+2
   end
end

并发现函数重载在 Ruby 中不起作用.还有哪些方法可以让代码遵守OCP?

and found out that function overloading does not work in Ruby. What are other methods through which the code can be made to obey OCP?

我本来可以去的:

class Fun
  def park(i)
      i=i+2 if i.class==1.class 
      puts i if i.class=="asd".class
  end
end

但这违反了 OCP.

推荐答案

你可以这样做:

class Parent
  attr_reader :s

  def initialize(s='')
    @s = s
  end

  def park
    puts s
  end
end

class Child1 < Parent
  attr_reader :x

  def initialize(s, x)
    super(s)
    @x = x
  end

  def park
    puts x 
  end
end

class Child2 < Parent
  attr_reader :y

  def initialize(s, y)
    super(s)
    @y = y
  end

  def park
    puts y
  end
end


objects = [
  Parent.new('hello'),
  Child1.new('goodbye', 1),
  Child2.new('adios', 2),
]

objects.each do |obj|
  obj.park
end

--output:--
hello
1
2

或者，也许我忽略了你的一个曲折:

Or, maybe I overlooked one of your twists:

class Parent
  attr_reader :x

  def initialize(s='')
    @x = s
  end

  def park
    puts x
  end
end

class Child1 < Parent
  def initialize(x)
    super
  end

  def park
    x + 2 
  end
end

class Child2 < Parent
  def initialize(x)
    super
  end

  def park
    x * 2
  end
end


objects = [
  Parent.new('hello'),
  Child1.new(2),
  Child2.new(100),
]

results = objects.map do |obj|
  obj.park
end

p results

--output:--
hello
[nil, 4, 200]

另一个使用 blocks 的例子，类似于匿名函数.您可以将所需的行为作为函数传递给 park():

And another example using blocks, which are like anonymous functions. You can pass in the desired behavior to park() as a function:

class Function
  attr_reader :block

  def initialize(&park)
    @block = park 
  end

  def park
    raise "Not implemented"
  end
end


class StringFunction < Function
  def initialize(&park)
    super
  end

  def park
    block.call
  end
end

class AdditionFunction < Function
  def initialize(&park)
    super
  end

  def park
    block.call 1
  end
end

class DogFunction < Function
  class Dog
    def bark
      puts 'woof, woof'
    end
  end

  def initialize(&park)
    super
  end

  def park
    block.call Dog.new
  end
end


objects = [
  StringFunction.new {puts 'hello'},
  AdditionFunction.new {|i| i+2},
  DogFunction.new {|dog| dog.bark},
]

results = objects.map do |obj|
  obj.park
end

p results

--output:--
hello
woof, woof
[nil, 3, nil]

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