How are symbols used to identify arguments in ruby methods

Question

I am learning rails and going back to ruby to understand how methods in rails (and ruby really work). When I see method calls like:

validates :first_name, :presen         


        

Answer 1

Symbols are not limited to hashes. They are identifiers, without the extra storage space of a string. It's just a way to say "this is ...."

A possible function definition for the validates call could be (just to simplify, I don't know off the top of my head what it really is):

def validates(column, options)
   puts column.to_s
   if options[:presence]
     puts "Found a presence option"
   end
 end

Notice how the first symbol is a parameter all of its own, and the rest is the hash.