[boost] [endian] Empty Base Class trouble implementing endian wrappers.

From: me22 (me22.ca_at_[hidden])
Date: 2006-06-08 00:04:28

I've been working on Yuval's suggestion of  (little|big|native)_endian
wrappers, but ran into a problem.  On fundamental types, the wrapper
works fine, and Beman's integer_cover_operators made it easy to add
support for integer operations. ( However, why does
integer_cover_operators use operators<T> and not
operators2<T,IntegerType> ?  I needed to change that to solve an
ambiguity error. )

The problem comes when wrapping my (newly reimplemented) exact type.
In that case, deriving the wrapper from integer_cover_operators adds 1
byte :
sizeof( long ) =        0x4
sizeof( boost::big_endian< long > ) =   0x4
sizeof( boost::exact<24> ) =    0x3
sizeof( boost::big_endian< boost::exact<24> > ) =       0x4

I could just have a get member function in the wrappers, but that
loses much of the elegance.  Any suggestions for solving this?

~ Scott McMurray

P.S. exact came out quite nicely, imho:
CHAR_BIT*sizeof( boost::exact<24>[2] ) =        48
CHAR_BIT*sizeof( boost::exact<24,signed,16>[2] ) =      64
CHAR_BIT*sizeof( boost::exact<32,unsigned>[2] ) =       64
CHAR_BIT*sizeof( boost::exact<8,unsigned,16>[2] ) =     32
( std::numeric_limits< boost::exact<24> >::min() ) =    -8388608
( std::numeric_limits< boost::exact<24> >::min()-1 ) =  8388607
( std::numeric_limits< boost::exact<24> >::max() ) =    8388607
( std::numeric_limits< boost::exact<24> >::max()+1 ) =  -8388608
( std::numeric_limits< boost::exact<24,unsigned> >::min() ) =   0
( std::numeric_limits< boost::exact<24,unsigned> >::max() ) =   16777215