Greetings all,

I was hoping someone might be able to point me in the right direction. I'm
currently
using std::vector to maintain several lists whose objects are of unrelated
types (classes).
I've seen mentioned here and there a technique that uses 'void *' and
something called
'template specialization' that would reduce the amount of code generated for
the
std::vector's.

I don't fully understand how I might use std::vector<void *> without having
to constantly
cast object pointers to and from 'void *'. Might someone point me to a
resource that
would explain this technique in greater detail?

Regards,

Salvador Ducros
sducros@rogers.com

Salvador> I was hoping someone might be able to point me in the right
Salvador> direction. I'm currently using std::vector to maintain
Salvador> several lists whose objects are of unrelated types
Salvador> (classes). I've seen mentioned here and there a technique
Salvador> that uses 'void *' and something called 'template
Salvador> specialization' that would reduce the amount of code
Salvador> generated for the std::vector's.

I guess the first question to ask is this: Is the amount of code
in question a serious problem?

--
Andrew Koenig, ark@acm.org

"Salvador I. Ducros" <sducros@rogers.com> wrote in message news:<KHhVa.108206$zwL.21692@news04.bloor.is.net.c able.rogers.com>...[color=blue]
> Greetings all,
>
> I was hoping someone might be able to point me in the right direction. I'm
> currently
> using std::vector to maintain several lists whose objects are of unrelated
> types (classes).
> I've seen mentioned here and there a technique that uses 'void *' and
> something called
> 'template specialization' that would reduce the amount of code generated for
> the
> std::vector's.
>
> I don't fully understand how I might use std::vector<void *> without having
> to constantly
> cast object pointers to and from 'void *'. Might someone point me to a
> resource that
> would explain this technique in greater detail?
>
> Regards,
>
> Salvador Ducros
> sducros@rogers.com[/color]

If you are storing a known set of types, you might check out Boost's
tuple class: http://boost.org/libs/tuple/doc/tuple_users_guide.html

Doh... I posted another post, but forget to finish it first... (and I
can't reply to it directly as I'm using Google and it takes forever to
update)

Anyway, about Boost::tuple, I'm not sure if that'll help. It probably
won't reduce code bloat anyway... But it may, so that's why I
suggested it.

"Evan" <eed132@psu.edu> wrote in message
news:3f25c666.0307282046.6d466131@posting.google.c om...[color=blue]
> Doh... I posted another post, but forget to finish it first... (and I
> can't reply to it directly as I'm using Google and it takes forever to
> update)
>
> Anyway, about Boost::tuple, I'm not sure if that'll help. It probably
> won't reduce code bloat anyway... But it may, so that's why I
> suggested it.[/color]

I'll check it out. It sounds like it might be useful for something else I've
been working on. Thanks,

Salvador I. Ducros
sducros@rogers.com

In article <RuzVa.5892$QsW1.959@news01.bloor.is.net.cable.rog ers.com>,
Salvador I. Ducros <sducros@rogers.com> wrote:

| "Andrew Koenig" <ark@acm.org> wrote in message
| news:yu99ptju6kte.fsf@tinker.research.att.com...
| > Salvador> I was hoping someone might be able to point me in the right
| > Salvador> direction. I'm currently using std::vector to maintain
| > Salvador> several lists whose objects are of unrelated types
| > Salvador> (classes). I've seen mentioned here and there a technique
| > Salvador> that uses 'void *' and something called 'template
| > Salvador> specialization' that would reduce the amount of code
| > Salvador> generated for the std::vector's.
| >
| > I guess the first question to ask is this: Is the amount of code
| > in question a serious problem?
| >
| > --
| > Andrew Koenig, ark@acm.org
|
| No. Not a problem. I simply wanted to educate myself about ways to avoid
| code bloat when using STL (& templates in general) for if and when it ever
| becomes a problem.
|
| On the other hand, I do find the amount of code being generated a bit much.
| I was able to reduce the code size significantly by using a generic
| container
| implemented in plain C. I'd rather use STL which is why I started searching
| for ways of reducing code bloat when using STL (std::vector in this specific
| case).

Bjarne Stroustrup's excellent text: The C++ Programming Language"
devotes a small section to this technique. The Metrowerks
implementation goes beyond the "void* optimization" and implements this
code size optimization across all pods (e.g. unsigned short and short
also share the same code).

--
Howard Hinnant
Metrowerks