Question

I want a method to be used within another method and returns the arguments without the need of mentioning the argument names, something like return_arguments in the following.

def foo a, b, *c
  ... # part a
  p return_arguments
  ... # part b
end

foo(1, "blah blah", :a, :b)
... # return from part a
# => [1, "blah blah", :a, :b]
... # return from part b

Is this possible? I figured out that binding, local_variables, and eval may be used, but am not sure how to distinguish the arguments from other local variables defined in part a above. Is there a particular ordering rule for local_variables? If so, maybe I can use that together with arity to extract the arguments.

Answer 1

It’s definitely inefficient, but here’s a solution (although you probably should be using a hash like @tadman mentioned):

set_trace_func proc { |e,_,_,i,b,_|
   if e == 'call'
      p = method(i).parameters
      @arguments = p.map {|p| eval(p[1].to_s,b)}
   end
}

def foo a, b, *c
   a = 50
   b = 3
   return @arguments
   a = 11
   b = 2
end

p foo(1, "blah blah", :a, :b)