QtD is suspended

[Michel Fortin]

On 2010-09-17 21:08:29 -0400, Walter Bright <newshound2 at digitalmars.com> said:

> Andrei Alexandrescu wrote:
>> On 9/17/10 10:48 CDT, Michel Fortin wrote:
>>> I understand the intent quite well. I'm talking about what happens if
>>> the source is const?
>> 
>> The whole point is, mutation is the motivator. If you copy an empty 
>> hash, no problem because the receiver can't mutate it.
> 
> Wouldn't copying a ref counted object require mutating the original?

This is an interesting point. Reference counting requires updating the 
reference counter which lives alongside the referenced memory. So if 
you have a const reference-counting struct, you can't make a copy of it 
because const will transitively apply to the counter too, preventing it 
from being incremented.

I'm not sure why you're talking about mutating "the original" though. 
You don't need to update the original smart pointer struct as the 
reference counter lives with the referenced memory to which you have 
access in postblit.

-- 
Michel Fortin
michel.fortin at michelf.com
http://michelf.com/