def from_prototype(prototype)
      prototype.split(/, */).each do |arg|
        arg = arg.split(" ")
        raise InvalidClassDefinition if arg.size != 2
        dir, arg = arg
        if arg =~ /:/
          arg = arg.split(":")
          name, sig = arg
        else
          sig = arg
        end
        case dir
        when "in"
          add_fparam(name, sig)
        when "out"
          add_return(name, sig)
        end
      end
      self
    end
def from_prototype(prototype)
      prototype.split(/, */).each do |arg|
        arg = arg.split(" ")
        raise InvalidClassDefinition if arg.size != 2
        dir, arg = arg
        if arg =~ /:/
          arg = arg.split(":")
          name, sig = arg
        else
          sig = arg
        end
        case dir
        when "in"
          add_fparam(name, sig)
        when "out"
          add_return(name, sig)
        end
      end
      self
    end
Add parameter types by parsing the given _prototype_.