On Tue, 27 Dec 2011 03:47:50 +0100, Andrei Alexandrescu
<seewebsiteforem...@erdani.org> wrote:
On 12/26/11 11:25 AM, Andrei Alexandrescu wrote:
[snip]
Destroy.
Walter indeed just destroyed me over the phone: I conflated reference
counting with copy-on-write. Essentially instead of defining a reference
type that's garbage-collected, I defined a value type that has cow.
Which is not bad! Check out the quick fix at
http://pastebin.com/HHw06qrc.
With that, cow is a sheer policy. With the magic of opDispatch it looks
like we can define reference counted containers _and_ value containers -
all in very little code.
The perspectives here are extremely exciting. The question remains how
to best package this awesome array of options to maximize coherence. So
we have:
1. "Basic" containers - reference semantics, using classic garbage
collection
Creating a final class wrapper using opDispatch and a value container
as a field might be an option that mixes well with the other wrappers.
2. Reference counted containers - still reference semantics, using
reference counting
Can't this be merged with std.typecons.RefCounted?
3. COW containers - value semantics, using reference counting to make
copying O(1).
If it works correctly this is a fully transparent COW wrapper, never seen
anything like that in C++.
It deserves to be a separate wrapper in std.typecons or so.
How to we provide an Apple-style nice wrapping to all of the above?
Andrei
Implementing containers as value types with deep-copy and
providing the three wrappers seems the most flexible approach.
The are applications where values are sufficient, e.g. global lists.
for the naming:
struct DListImpl; // public
alias ClassWrapper!DListImpl DList;
optionally add aliases:
alias RefCounted!DListImpl RefCountedDList;
alias CopyOnWrite!DListImpl CopyOnWriteDList;
Given that it would be used consistently across the whole
std.container modules it's an easy scheme to learn.
