Ruby - 打印变量名，然后是它的值 [英] Ruby - print the variable name and then its value

问题描述

编写允许我用 Ruby 编写此代码的函数(或类似 DSL 的东西)的最佳方法是什么?我将如何构造函数 write_pair?

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

可以吗?寻找最简单的方法来做到这一点.

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

推荐答案

当然有可能！

我的解决方案通过 Object#object_id 身份测试 var:http://codepad.org/V7TXRxmL
它在绑定传球风格中瘫痪了......
虽然它只适用于本地变量，但可以很容易地通用"添加其他范围变量列表方法，如 instance_variables 等.

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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