Re: [boost] Proxy --- an indirect container adaptor

From: Daryle Walker (darylew_at_[hidden])
Date: 2004-02-29 08:19:47

On 2/20/04 7:39 AM, "Christian Engström" <christian.engstrom_at_[hidden]>
wrote:

> Is the following design valid, and if so, would it make a useful
> addition to the Boost library? I enclose a draft implementation, and
> look forward to any comments.

1.  I think that someone else has already been working on something like
this.  (It should be in our YahooGroups files area.)

2.  I think that person has done all the containers.  (I'm not sure.)  More
importantly, the other submission is a _lot_ bigger, probably because s/he
has thought through more of the issues (or maybe it's over-engineered).

3.  I don't remember how the other guy did his/her implementation, but I
have a hint anyway.  If you're doing an indirect container that elements act
like a smart-pointer, that doesn't actually mean that you should actually
use a vector< smart_ptr<T> >.  I think you should use something like a
vector<T *> and handle the smartness yourself to save memory.

4.  I know you have an issue with someone else on this list over your
iterator/dereferencing policy, but I have an issue with it besides standard
compliance.  It's not consistent.  The "->" gives the final object directly,
but the "*" and "[]" only go one step and return a proxy.  I don't like this
mix.  You claim that the directness is not needed for the latter two
operators because proxy<T> takes assignments from T and converts to T.  If
so, then what is the point of using the proxy directly?  Can I ever have an
use for a "proxy<T>" object as itself?  If not, then I don't need to be
forced to deal with it and you should change "*" and "[]" to also return T&
directly.  (Your "proxy<T>" <-> T conversion policy could fail in some
template contexts.)

-- 
Daryle Walker
Mac, Internet, and Video Game Junkie
darylew AT hotmail DOT com