RE: [boost] Fixed-Point Decimal Interface

From: Fernando Cacciola (fcacciola_at_[hidden])
Date: 2001-05-14 08:54:38

----- Original Message -----
From: Bill Seymour <bsey_at_[hidden]>
To: <boost_at_[hidden]>
Sent: Monday, May 14, 2001 9:20 AM
Subject: Re: [boost] Fixed-Point Decimal Interface

> I've been thinking about some of the points that Skaller
> and others brought up.  How's this?
>
> - I agree that functions such as abs() should be friends,
>   not members.  I'm concerned, though, that some compilers
>   can't handle template friends.  As a compromise, I suggest
>   leaving such functions in the class as helpers for the free
>   functions, and either leaving them undocumented or (better IMO)
>   documenting them as implementation details that have to be
>   public for portability to non-conforming implementations.
>
All right. But have them only inside apropriate #ifdef/#endif pairs, so that
conformant
compilers don't even see them.

> - I see Skaller's point about the two-argument ctor being
>   confusing.  At first I thought about suggesting to users
>   that they think of the comma as a decimal point; but then
>   I caught myself writing an octal constant. 8-)  I think
>   I've found a use for this ctor, though:
>
>     numeric_limits< decimal<Scale> >::epsilon();
>
>   returns decimal<Scale>(0, 1).  I suggest making this ctor
>   one of the "public implementation details" mentioned above.
>
Perhaps 'Named Constructors' can help here:

template<int Scale = >
class decimal
{
public:

  static decimal<Scale> CreateThisWay ( int_type ipart, int_type frac ) ;

}

However, I can't come up with a sensible name so this might be just as
useless!

> - I still think that users ought to be able to mix decimals
>   of different scale factors in expressions.  I suggest that
>   the result type always be the type of the left-hand argument.
>   Users can always get a different type with an explicit cast

I would use max(scaleL,scaleR);

Fernando Cacciola
Sierra s.r.l.
fcacciola_at_[hidden]
www.gosierra.com