“super”和“super do |u|”的区别使用设计的上下文

Question

好的，所以我想我得到了超级 does 独立。基本上在设计中，如果Users::RegistrationsController < Devise::RegistrationsController，那么在任何操作上，拥有super 将首先调用父Devise::RegistrationsController 中相同命名操作的逻辑，然后再调用您编写的内容。

换句话说……

class Devise::RegistrationsController
  def new
    puts "this is in the parent controller"
  end
end

class Users::RegistrationsController < Devise::RegistrationsController
  def new
    super
    puts "this is in the child controller"
  end
end

# Output if users#new is run would be:
# => "this is in the parent controller"
# => "this is in the child controller"

# If super were reversed, and the code looked like this
# class Users::RegistrationsController < Devise::RegistrationsController
  #  def new
    #  puts "this is in the child controller"
    #  super
  #  end
#  end
# Then output if users#new is run would be:
# => "this is in the child controller"
# => "this is in the parent controller"

我很好奇的是我见过一些人这样做：

class Users::RegistrationsController < Devise::RegistrationsController
  def new
    super do |user|
      puts "something"
    end
  end
end

我很难理解do block 正在完成的工作。就我而言，在创建资源（用户）之后，我想对该资源（用户）调用一个附加方法。

当前代码：

class Users::RegistrationsController < Devise::RegistrationsController
  def new
    super do |user|
      user.charge_and_save_customer
      puts user.inspect
    end
  end
end

我只是想知道这与做有什么不同：

class Users::RegistrationsController < Devise::RegistrationsController
  def new
    super
    resource.charge_and_save_customer
    puts resource.inspect
  end
end

如果有帮助，我在下面包含了父 Devise::RegistrationsController 代码：

def new
  build_resource({})
  set_minimum_password_length
  yield resource if block_given?
  respond_with self.resource
end

Answer 1

让我试着解释一下这里发生了什么：

class Users::RegistrationsController < Devise::RegistrationsController
  def new
    super do |user|
      user.charge_and_save_customer
      puts user.inspect
    end
  end
end

当您调用super 时，您将返回父new 操作，因此现在将执行以下代码：

def new
  build_resource({})
  set_minimum_password_length
  yield resource if block_given?
  respond_with self.resource
end

但是等等...这里是一个yield，所以它将当前的resource 生成给块，你可以把块想象成一个方法，它需要一个参数（user），这里是@ 987654328@（来自父级）将是参数：

# Here resource is assigned to user
user.charge_and_save_customer
puts user.inspect

现在，由于该块已完全执行，它将再次开始执行超级：

respond_with self.resource