Re: [boost] Fixed-Point Decimal Interface

From: Bill Seymour (bsey_at_[hidden])
Date: 2001-05-14 07:20:26

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.

- 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.

- 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 tried a little coding using both BCD and one-digit-per-char
  representations and found them _very_ expensive.  I think
  Skaller is right about doing just the 64-bit-int version.

--Bill Seymour