Re: [boost] Interest in a flyweight library?

From: Joaquín Mª López Muñoz (joaquin_at_[hidden])
Date: 2006-06-29 12:04:49

me22 ha escrito:

> On 6/28/06, Joaquín Mª López Muñoz <joaquin_at_[hidden]> wrote:
> > During some conversations with a colleague I came up with a very
> > sketchy realization of what could be converted, if there is interest,
> > in a flyweight library. Please see flyweight.hpp at Vault/Patterns:
> >
> > Additionally, comparison of flyweight objects can be made faster than
> > that of the underlying type T, since we it reduces to pointer comparison
> >
> Very nice!

Thank you!

> A few comments:
> - What's y?
>   void swap(flyweight& x)
>
>   {
>
>         std::swap(x.h,y.h);
>
>   }

This is my error, please replace with

   std::swap(h,x.h);

I've uploaded a corrected version of flyweight.hpp to the Vault.

> - I'm not convinced operator< should be in terms of the pointer.  x<y
> being different from (T&)x < (T&)y seems like an easy source of
> errors.

Yes, you've got a point here. My design ideas involve turning flyweight
into a policy-controlled class so that the user can select this kind of
things. I agree with you the default should be T-compatible operator<
and only pointer-based when the user explicitly selects it.

> ~ Scott McMurray
>
> <OT> Has anyone proposed a good way of doing wrapping for C++0x?  That
> problem keeps coming up...

A poor man's approach to wrapping can be taken with Jonathan
Turkanis' BIL library

http://www.kangaroologic.com/interfaces/

which has also IMHO an immense potential for all kinds of applications.
Unfortunately, seems like Jonathan is not actively pursuing promoting this
into Boost :(

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo