Implementing .dup / clone for class hierarchies

[Bill Baxter]

Bill Baxter wrote:
> guslay wrote:
>> Bill Baxter Wrote:

> For some reason everyone seemed to like Mikola's suggestion of 'clone' 
> for deep copy and 'dup' for shallow copy, but the odd thing about that 
> is that .dup on built-in arrays is a deep copy.  

I realized this isn't quite true.  .dup on arrays is depth=1, rather 
than truly "deep" (depth=N) or shallow (depth=0).  So maybe Mikola was 
right.

We can take 'dup' to mean "copy one more level than you'd get from the 
rudimentary assignment: a = b".  So for built-in arrays  dup means copy 
the stuff pointed to by ptr, but for a class, stuff pointed to by a ptr 
member wouldn't be copied.

--bb