[phobos] CustomFloat

[Lars Tandle Kyllingstad]

On Sat, 2010-06-05 at 10:42 -0400, David Simcha wrote:
> Robert Jacques (who I know offline and, in fact, was the person who 
> introduced me to D) has massively improved/debugged CustomFloat and 
> asked me to post it for review and commit it to Phobos.  See the 
> attached file.  If everyone's happy with it, I'll replace the current 
> impl in std.numeric and check it in.

It's awesome that someone's working on this -- I've seen people
complaining about the state of CustomFloat several times.  (I think the
last time was when we discussed the possibility of using an 80-bit
CustomFloat in Masahiro's msgpack library, to wrap 80-bit reals on
systems that don't support them.)

That said, I'm having some problems with it.  Looking at the code and
documentation, the following should be correct usage:

        alias CustomFloat!16 float16;

However, compiling it with DMD 2.046, I get the errors

        customfloat.d(430): Error: template instance ToBinary!(real)
        does not match template declaration ToBinary(F) if
        (is(CustomFloat!(F.sizeof * 8)))
        customfloat.d(430): Error: ToBinary!(real) is used as a type
        ...

-Lars