Ruby - print the variable name and then its value

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 = bindingdef 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 worksusername1 = "tyndall"username  = "tyndall"username3 = "tyndall"# the result:write_pair(username)# username: tyndall

If it's possible for you to use a symbol instead of the variable name, you could do something like this:

def wp (s, &b)  puts "#{s} = #{eval(s.to_s, b.binding)}"end

In use:

irb(main):001:0> def wp (s, &b)irb(main):002:1>   puts "#{s} = #{eval(s.to_s, b.binding)}"irb(main):003:1> end=> nilirb(main):004:0> var = 3=> 3irb(main):005:0> wp(:var) {}var = 3

Note that you must pass the empty block {} to the method or it cannot get the binding to evaluate the symbol.

You can't actually get a variable's name in Ruby. But you could do something like this:

data = {"username" => "tyndall"}

Or even,

username = "tyndall"data = {"username", "password", "favorite_color"}data.each { |param|   value = eval(param)   puts "#{param}: #{value}"}