如何编写自己的loop_until? [英] How do I write my own loop_until?

问题描述

我正在练习我的Ruby元编程，并尝试编写自己的循环方法，该方法将处理侦听套接字的大多数丑陋现象，但使程序员有机会指定循环中断条件和某些事情在每个IO.select/sleep周期之后执行.

I'm practicing my Ruby meta-programming and trying to write my own loop method that will handle most of the ugliness in listening to a socket, but give the programmer the chance to specify the loop break condition and a block of things to do after each IO.select/sleep cycle.

我想要写的是这样的:

x = 1
while_listening_until( x == 0 ) do
  x = rand(10)
  puts x
end

我能够做的是:

def while_listening_until( params, &block )

  break_cond = params[ :condition ] || "false"
  loop {
    #other listening things are happening here
    yield
    break if params[:binding].eval( break_cond )
  }
end

x = 1
while_listening_until( :condition => "x==0", :binding => binding() ) do
  x = rand(10)
  puts x
end

那么，如何使所有eval和绑定的丑陋消失?

So, how do I make all that eval and binding ugliness go away?

推荐答案

这是lambda派上用场的地方:

This is where lambdas are handy:

def while_listening_until( condition, &block )
  loop {
    #other listening things are happening here
    yield
    break if condition.call
  }
end

x = 1
while_listening(lambda{ x == 0 }) do
  x = rand(10)
  puts x
end

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