Re: Decimal: Formal review begins.

From: Robert Ramey (ramey_at_[hidden])
Date: 2025-01-16 19:56:02

On 1/16/25 10:25 AM, Peter Dimov via Boost wrote:

> IEEE floating point doesn't have undefined behavior, so it's always "safe" in
> the "no undefined behavior" sense. (Assuming that floating point exceptions
> are disabled. When they are enabled, it's not so clear.)

For better or worse, safe numerics goes beyond undefined behavior in 
trapping behavior which fails to replicate the arithmetical behavior of 
the underlying type.  This is meant to guarantee the we always get a 
valid arithmetic result or a trap.

In any case, knowing that decimal32 et al fulfills the requirements for 
Numeric<T> should be good enough.  If it's not, that's something that 
should be addressed within safe numerics.

In a related note, the interval arithmetic library should also work with 
decimal32.  I don't know how much this library is used or even it's 
maintained.  But I would be curious if it's usable with decimal32.  I 
had looked at the library as the implementation of safe numerics 
requires this functionality, but I found it unsuitable for non-floating 
types - ie integer types.

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