Re: [boost] [Any] Reference counting

Subject: Re: [boost] [Any] Reference counting
From: Michael Howell (mhowell123_at_[hidden])
Date: 2009-04-05 21:06:46

Steven Watanabe <watanabesj_at_[hidden]> wrote:
> Have you read http://www.gotw.ca/gotw/045.htm?
I haven't read it, and have looked into atomic numbers, but couldn't find the 
"Boost Way" to do it (except perhaps poking around with shared_ptr innards). I 
wanted to use intrusive counts, since we have control over the object we are 
sharing.

Thorsten Ottosen <thorsten.ottosen_at_[hidden]> wrote:
>If you want to improve the performance of any, the thing to do is to add 
> a small buffer optimization such that all buildin types (or equally 
> small UDT) are created on the stack.
I'll look into that.

Mathias Gaunard <mathias.gaunard_at_[hidden]> wrote:
> Also, any is a value type. We do not want it to have reference 
> semantics. So you'd need to use COW.
Actually, copy on write/implicit sharing is what I was proposing, if you had 
looked at the code.
> Hence this is fairly useless, especially since we're getting move 
> semantics soon.
"Soon" is relative. The trunk GCC may support it instantly (may already), but 
Debian Stable won't, nor will MSVC (both which will be used for a good while). 
Also, you usually copy the value when you store it, which may or may not 
involve writing. For example:
#include <boost/any.hpp>
using namespace boost;
struct example {
    any variable;
};
int main() {
    example object;
    example object2;
    any value = "I Love Boost!";
    object.variable = value;
    object2.variable = value;
    return 0;
}

Thanks for replying, everyone.

-- 
Michael Howell 
mhowell123_at_[hidden]