MacRuby way

person = Person.new
person.name
person.name = name
person.setFirstName(first, lastName:last)

Obj-C way

Person *person = [Person new];                // create an instance of the Person class.

[person name];                                // send selector 'name'.
[person setName:name];                        // send selector 'setName:', passing the 'name' variable as an argument. 
[person setFirstName:first lastName:last];    // send selector 'setFirstName:lastName:', 
                                              // passing both 'first' and 'last' variables as arguments.