Re: [boost] [visit_each] doc? (was Re: Interest for policy based smart pointer (smart_ptr)

From: David Abrahams (dave_at_[hidden])
Date: 2006-01-20 17:15:33

Larry Evans <cppljevans_at_[hidden]> writes:

> On 01/20/2006 10:47 AM, Larry Evans wrote:
>> On 01/20/2006 10:00 AM, David Abrahams wrote:
> [snip]
>>>http://www.boost.org/doc/html/signals/s05.html#id2739308
> [snip]
>> I'll read the docs to see if it'll work.
> [snip]
> The file:
>
>    http://www.boost.org/doc/html/visit_each.html
>
> has:
>
>    visit_each mechanism allows a visitor to be applied to every
>    subobject in a given object.
>
> but there's no definition of subobject or object.  

These terms are defined in the C++ standard.

> Is a subobject
> any instance of a class, 

Or a builtin type.

> or only those derived from signals::trackable?
>
> The file also contains:
>
>    other uses may surface if used universally (e.g., conservative
>    garbage collection).
>
> does the "conservative" qualifier mean the subobjects are located
> conservatively (e.g. comaring each word in the containing object
> with some flag value)?

"Conservative garbage collection" usually means that a memory block is
considered to be referenced as long as there's a bit pattern somewhere
that *could* be a pointer into it.  I think the word "conservative" is
just wrong in this context and the author meant the opposite -- that
memory is considered to be referenced iff there is a real pointer into
that memory -- but I could be mistaken.

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com