如何实现“回调”在Ruby？

问题描述

我不确定Ruby中C风格回调的最好方法 - 或者有更好的方法（不像C）。在C中，我会做如下：

I'm not sure of the best idiom for C style call-backs in Ruby - or if there is something even better ( and less like C ). In C, I'd do something like:

void DoStuff( int parameter, CallbackPtr callback )
{
  // Do stuff
  ...
  // Notify we're done
  callback( status_code )
}

一个好的Ruby对等体是什么？基本上我想调用一个传递的类方法，当一个特定的条件满足DoStuff

Whats a good Ruby equivalent? Essentially I want to call a passed in class method, when a certain condition is met within "DoStuff"

推荐答案

这不是惯用的，将是：

def my_callback(a, b, c, status_code)
  puts "did stuff with #{a}, #{b}, #{c} and got #{status_code}"
end

def do_stuff(a, b, c, callback)
  sum = a + b + c
  callback.call(a, b, c, sum)
end

def main
  a = 1
  b = 2
  c = 3
  do_stuff(a, b, c, method(:my_callback))
end

习惯的方法是传递一个块而不是一个方法的引用。块对独立方法的一个优点是上下文 - 块是 ，因此它可以引用来自它声明的作用域的变量。这减少了do_stuff需要传递给回调的参数的数量。例如：

The idiomatic approach would be to pass a block instead of a reference to a method. One advantage a block has over a freestanding method is context - a block is a closure, so it can refer to variables from the scope in which it was declared. This cuts down on the number of parameters do_stuff needs to pass to the callback. For instance:

def do_stuff(a, b, c, &block)
  sum = a + b + c
  yield sum
end

def main
  a = 1
  b = 2
  c = 3
  do_stuff(a, b, c) { |status_code|
    puts "did stuff with #{a}, #{b}, #{c} and got #{status_code}"
  }
end

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