Question

I’m trying to create a number of objects from a class.

class Class
    def initialize (name=nil, age = nil, weight = nil)
        @name = name
        @age = age
        @weight = weight
    end
end
p1 = Class.new("Joe", 12, 135)
p2 = Class.new("Jack", 29, 200)

The problem is that the objects are not going to hold the same number of parameter. If I try to create a person that “does’nt have” a weight:

p3 = Class.new("Jill", 44)

This will affect the previously created objects, by removing their wheight as well, which is not what I intended to do. Is there a way to get around this, closing classes?
Or am I missing something vital?

Answer 1

My IRB session:

1.9.2p290 :001 > class MyClass
1.9.2p290 :002?>   def initialize(name = nil, age = nil, weight = nil)
1.9.2p290 :003?>     @name = name
1.9.2p290 :004?>     @age = age
1.9.2p290 :005?>     @weight = weight
1.9.2p290 :006?>     end
1.9.2p290 :007?>   end
 => nil 
1.9.2p290 :010 > p1 = MyClass.new("Joe", 12, 135)
 => #<MyClass:0x00000002226a08 @name="Joe", @age=12, @weight=135> 
1.9.2p290 :011 > p2 = MyClass.new("Jack", 29, 200)
 => #<MyClass:0x00000002212b98 @name="Jack", @age=29, @weight=200> 
1.9.2p290 :013 > p3 = MyClass.new("Jill", 44)
 => #<MyClass:0x000000021c9600 @name="Jill", @age=44, @weight=nil> 
1.9.2p290 :014 > ap p1
#<MyClass:0x02226a08
    @age = 12,
    @name = "Joe",
    @weight = 135
>
 => #<MyClass:0x00000002226a08 @name="Joe", @age=12, @weight=135> 
1.9.2p290 :015 > ap p2
#<MyClass:0x02212b98
    @age = 29,
    @name = "Jack",
    @weight = 200
>
 => #<MyClass:0x00000002212b98 @name="Jack", @age=29, @weight=200> 
1.9.2p290 :016 > ap p3
#<MyClass:0x021c9600
    @age = 44,
    @name = "Jill",
    @weight = nil
>
 => #<MyClass:0x000000021c9600 @name="Jill", @age=44, @weight=nil> 

As you see there is no global override of @weight.