如何使用反射获取参数名称 [英] How to get argument names using reflection

问题描述

我想在 Ruby 中做一些相当繁重的反射.我想创建一个函数，该函数返回调用堆栈更高层的各种调用函数的参数名称(仅高一个就足够了，但为什么要停在那里?).我可以使用 Kernel.caller，转到文件并解析参数列表，但这会很丑陋且不可靠.

I would like to do some fairly heavy-duty reflection in Ruby. I want to create a function that returns the names of the arguments of various calling functions higher up the call stack (just one higher would be enough but why stop there?). I could use Kernel.caller, go to the file and parse the argument list but that would be ugly and unreliable.

我想要的功能将按以下方式工作:

The function that I would like would work in the following way:

module A
  def method1( tuti, fruity) 
    foo
  end
  def method2(bim, bam, boom)  
    foo
  end
  def foo
    print caller_args[1].join(",") #the "1" mean one step up the call stack
  end

end

A.method1
 #prints "tuti,fruity"
A.method2
 #prints "bim, bam, boom"

我不介意使用 ParseTree 或一些类似的工具来完成这项任务，但看看 Parsetree，如何将其用于此目的并不明显.创建像 this 这样的 C 扩展是另一种可能性，但如果有人已经为我做的.

I would not mind using ParseTree or some similar tool for this task but looking at Parsetree, it is not obvious how to use it for this purpose. Creating a C extension like this is another possibility but it would be nice if someone had already done it for me.

我可以看出我可能需要某种 C 扩展.我想这意味着我的问题是 C 扩展的哪种组合最容易工作.我不认为 caller+ParseTree 本身就足够了.

I can see that I'll probably need some kind of C extension. I suppose that means my question is what combination of C extension would work most easily. I don't think caller+ParseTree would be enough by themselves.

至于我为什么要这样做，与其说自动调试"，不如说我想用这个功能来自动检查函数的调用和返回条件:

As far as why I would like to do this goes, rather than saying "automatic debugging", perhaps I should say that I would like to use this functionality to do automatic checking of the calling and return conditions of functions:

def add x, y 
  check_positive
  return x + y
end

如果 x 和 y 不是正数，check_positive 会抛出异常.显然，还有更多内容，但希望这能提供足够的动力.

Where check_positive would throw an exception if x and y weren't positive. Obviously, there would be more to it than that but hopefully this gives enough motivation.

推荐答案

我建议你看看 Merb 的 action-args 库.

I suggest you take a look at Merb's action-args library.

require 'rubygems'
require 'merb'

include GetArgs

def foo(bar, zed=42)
end

method(:foo).get_args # => [[[:bar], [:zed, 42]], [:zed]]

如果你不想依赖 Merb，你可以从 github 中的源代码.

If you don't want to depend on Merb, you can choose and pick the best parts from the source code in github.

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