Ruby - 输出变量名称和值 [英] Ruby - print the variable name and then its value

问题描述

编写一个函数（或某种DSL文件）的最佳方法是让我可以在Ruby中编写这段代码。我将如何构造write_pair函数？

pre $ username =tyndall
write_pair username
＃where write_pair用户名输出
用户名：tyndall


有可能吗？寻找最简单的方法来做到这一点。

解决方案

确实有可能！

我的解决方案通过Object＃object_id identity来测试var： http： //codepad.org/V7TXRxmL

它在绑定传递风格中变成了残缺......

虽然它仅适用于本地变量，但它可以很容易地制作通用增加了其他范围变量列表方法的使用，如 instance_variables 等。

 ＃这个函数必须在这样的地方定义
＃...以便捕获变量的绑定... cheesy 
＃否则我们会被卡住调用者的额外参数
 @_binding = binding 
 def write_pair（p，b = @_binding）
 eval（
 local_variables.each do | v | 
如果eval（v.to_s + \.object_id \）==+ p.object_id.to_s +
 puts v.to_s +'：'+ \+ p.to_s + \
 end 
 end 
，b）
 end 
 
＃如果绑定是一个问题，只需在这里执行：
＃ write_pair = lambda {| p | write_pair（p，binding）} 
 
＃只是一些测试变量，以确保它能正常工作
 username1 =tyndall
 username =tyndall
 username3 = tyndall
 
＃结果：
 write_pair（username）
＃username：tyndall 
  

What is the best way to write a function (or something DSLish) that will allow me to write this code in Ruby. How would I construct the function write_pair?

username = "tyndall"
write_pair username
# where write_pair username outputs 
username: tyndall

Is it possible to do? Looking for the most simple way to do this.

解决方案

Sure it is possible!

My solution tests the var by Object#object_id identity: http://codepad.org/V7TXRxmL
It's crippled in the binding passing style ...
Although it works just for local vars yet, it can be easily be made "universal" adding use of the other scope-variable-listing methods like instance_variables etc.

# the function must be defined in such a place 
# ... so as to "catch" the binding of the vars ... cheesy
# otherwise we're kinda stuck with the extra param on the caller
@_binding = binding
def write_pair(p, b = @_binding)
  eval("
    local_variables.each do |v| 
      if eval(v.to_s + \".object_id\") == " + p.object_id.to_s + "
        puts v.to_s + ': ' + \"" + p.to_s + "\"
      end
    end
  " , b)
end

# if the binding is an issue just do here:
# write_pair = lambda { |p| write_pair(p, binding) }

# just some test vars to make sure it works
username1 = "tyndall"
username  = "tyndall"
username3 = "tyndall"

# the result:
write_pair(username)
# username: tyndall

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