在 ruby 方法上定义自定义回调

Question

我有许多服务 classes，其中 call 方法的参数有所不同。

我想在每个 call 方法的末尾调用一个函数 notify。我不想修改那些服务 classes 但我愿意修改基础 class。

我正在玩ActiveSupport::Callbacks，但它不能达到不修改服务的目的class。

require 'active_support'
class Base
  include ActiveSupport::Callbacks
  define_callbacks :notifier

  set_callback :notifier, :after do |object|
    notify()
  end

  def notify
    puts "notified successfully"
  end
end

class NewPost < Base
  def call
    puts "Creating new post on WordPress"
    # run_callbacks :notifier do
    #   puts "notifying....."
    # end
  end
end

class EditPost < Base
  def call
    puts "Editing the post on WordPress"
    # run_callbacks :notifier do
    #   puts "notified successfully"
    # end
  end
end

person = NewPost.new
person.call

问题为了运行回调，我需要取消注释代码。但是在这里你可以看到我需要修改现有的 classes 来添加 run_callbacks 块。但这不是我想要的。我可以轻松地调用 notify 方法而不用增加这种复杂性。

任何人都可以建议我如何找到解决方案 ruby 的方法吗？

Answer 1

我会这样做：

require 'active_support'
class Base
  include ActiveSupport::Callbacks
  define_callbacks :notifier

  set_callback :notifier, :after do |object|
    notify()
  end

  def notify
    puts "notified successfully"
  end

  def call
    run_callbacks :notifier do
      do_call
    end
  end

  def do_call
    raise 'this should be implemented in children classes'
  end
end

class NewPost < Base
  def do_call
    puts "Creating new post on WordPress"
  end
end

person = NewPost.new
person.call

另一种没有 ActiveSupport 的解决方案：

module Notifier
  def call
    super
    puts "notified successfully"
  end
end


class NewPost
  prepend Notifier

  def call
    puts "Creating new post on WordPress"
  end
end

NewPost.new.call

您应该检查您的 ruby 版本 prepend 是 "new" 方法 (2.0)

Answer 2

一般在继承类中设置回调。不确定你想从你的例子中实现什么，但从你最初的描述来看它应该是这样的：

require 'active_support'

class Base
  include ActiveSupport::Callbacks
  define_callbacks :call

  def call
    run_callbacks(:call) { puts "something is happening..." }
  end
end

class Post < Base
  set_callback :notify, :after, :call

  private

  def notify
    puts "new post!"
  end
end

post = Post.new
post.call

在 ruby 方法上定义自定义回调

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