On Feb 23, 3:59 ¨Âí¬ Òïâåòô Ëìåííå ¼óèïòôãõô®®®Àçïïçìåíáéì®ãïí¾ ÷òïôåº > On 23.02.2009 22:42, Yossef Mendelssohn wrote: > > I only pointed it out because there's no way (that I know of) to show > > that a and b point to the same object at one point if a Fixnum is > > used. You can use 'hi'.sub!, but there's no 1.succ! > > You can use #object_id for that - even for Fixnums. :-) Good point, though I still stick to my guns and say that showing this with a different object, like a String, is clearer. Seeing that two numbers have the same object_id doesn't carry the same weight as seeing that mutating the value of variable (as in a = 'hi'; a.upcase!) will change the value of another. Maybe I look at it something like trying to write a failing test before writing some code. Sure you can show that a = 3 b = a a.object_id == b.object_id # true But that's not very interesting because 3.object_id == 3.object_id. It's different with strings 'hi'.object_id == 'hi'.object_id # false a = 'hi' b = a a.object_id == b.object_id # true -- -yossef