是否可以在 Ruby 中执行 before_action(如在 Rails 中)? [英] Is it possible to do a before_action in Ruby (like in Rails)?

问题描述

是否可以在 Rails 等指定方法之前调用 before_action ?

Is it possible to call a before_action before some specified method like in rails?

class Calculator
  before_action { raise Exception, "calculator is empty" if @numbers.nil? }, 
                 only: [:plus, :minus, :divide, :times]

  def push number
    @numbers ||= [] 
    @numbers << number
  end

  def plus
    # ... 
  end

  def minus
    # ... 
  end

  def divide
    # ... 
  end

  def times
    # ... 
  end

    # ... 
end

推荐答案

您正在寻找的是 面向方面的编程 支持 ruby​​.有几个 gem 实现了这一点，例如 aquarium.

What you are looking for is Aspect oriented programming support for ruby. There are several gems implementing this, like aquarium.

不过，我认为，在您的情况下，一些懒惰的检查就足够了:

I think though, that in your case, some lazy checks will be sufficient:

class Calculator
  def numbers
    raise Exception, "calculator is empty" if @numbers.nil?
    @numbers
  end

  def push number
    @numbers ||= [] 
    @numbers << number
  end

  def plus
    numbers.inject(:+) # <-- will throw the correct Exception if `@numbers` is nil
    # ... 
  end

  def minus
    # ... 
  end

  def divide
    # ... 
  end

  def times
    # ... 
  end

    # ... 
end

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