Is there an analog of Python's vars() method in Ruby?

Question

In Python there is vars() method which returns a dictionary of names of local variables as keys, and their values, so it is possible to do something like this:

a = 1
b = 2
"%(a)s %(b)s" % vars()

Is there an analog of vars() in Ruby? The closest construct I can think of is

local_variables.inject({}) {|res,var| res[var] = eval(var.to_s); res}

Similar to what you came up with: http://stackoverflow.com/questions/430811/enumerate-or-list-all-variables-in-a-program-of-your-favorite-language-here/430861#430861 — Mark, Aug 23 '10 at 16:04
This is not what `vars()` is meant to be used for. As a matter of fact that's pretty bad. — Devin Jeanpierre, Aug 23 '10 at 18:41
Devin, can you explain your statement? What vars() is meant to be used for? And what is a disadvantage of the example? — dimus, Aug 25 '10 at 13:12

score 1 · Answer 1 · answered Aug 23 '10 at 18:49

1

The ruby equivalent of what you are doing is just

"#{a} #{b}"

Is there another reason you need vars()?

answered Aug 23 '10 at 18:49

John La Rooy

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score 1 · Accepted Answer · answered Aug 23 '10 at 19:23

You could implement it something like this, but it's not very pretty. And as gnibbler pointed out, it's just easier to use interpolation. About the only advantage I see to doing something like this is if the format string formats the same values multiple times. And even then, it would probably be easier to use a custom hash (instead of dumping vars into the formatter), or abstracting it into a method.

#!/usr/bin/env ruby

module Kernel
  def vars(b)
    Hash[
      (b.eval('local_variables')-[:_]).
      map{|v| [v,b.eval(v.to_s)]}
    ]
  end
end

a = 10
puts vars(binding)

Is there an analog of Python's vars() method in Ruby?

2 Answers2