Re: [Boost-users] Needs advices on design ( mpl or processor )

8 Jan 2012

      On 01/07/12 17:28, Larry Evans wrote:
...
On 01/07/12 02:42, Allan Nielsen wrote:
[snip]
...
void example1()
{
    // As you see, the expresions for calculating the offset get quite long,
    // and are not easy to maintain.
Here's where I don't understand why the calculation are done outside
the temple and then passed as args to the template.
Why not have a template do the calculations and accumulate the results,
somewhat like mpl::fold or the code I posted earlier?
...
C< CompressedEnum,
CompressedEnum::offset *
                            CompressedEnum::size >,
CompressedEnum
CompressedEnum::offset *
                                 CompressedEnum::size >::offset
            *
            CompressedEnum::offset *
                                 CompressedEnum::size >::size
       >
    > c1;
}
[snip]
The attached code produces output:
:eos_t::offset=9
:get_ol(T1)=2
:get_ol(T2)=0
:get_ol(T3)=0
:get<T3>=0
putting:
:get<T1>=0
:get<T2>=1
:get<T3>=2

The output before the putting: lines is caused by the obviously
erroneous initialization of the buffer (no Enum e's stored in
the buffer, only unsigned ints).  The output after the putting: lines
shows the effect of the put(Enum e).

However, be warned! I'm not sure all the casting within the get_ol
and put_ol is portable.

Is this about what you want?

I've looked briefly at Vicente's bit_mask library and it looks
more complicated; however, that extra complication is probably
because it provides extra capabilities.

HTH.

-Larry