Get The Name Of A Local Variable

Question

When developing & debugging, I sometimes wish I could write a 1-liner that dumped the names, types & values of a bunch of variables. The problem is I don\'t know ho

Answer 1

Here's a little bit of debug code I use all over the place (I stick it in a separate file so that it can be required wherever needed). It can be used two ways. Passed one or more values, it simply inspects them and writes the result to $stderr. But passed a block which returns one or more things, it writes them out with their names.

#!/usr/bin/ruby1.8

def q(*stuff, &block)
  if block
    s = Array(block[]).collect do |expression|
      value = eval(expression.to_s, block.binding).inspect
      "#{expression} = #{value}"
    end.join(', ')
    $stderr.puts s
  else
    stuff.each do
      |thing| $stderr.print(thing.inspect + "\n")
    end
  end
end

i = 1
q i       # => 1
q {:i}    # => i = 1

name = "Fred"
q [name, name.length]         # => ["Fred", 4]
q {[:name, 'name.length']}    # => name = "Fred", name.length = 4

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Note: The q function, and more, is now available in the cute_print gem.