Re: Equality operator overloading in ADA 83

[Mats Weber <Mats.Weber@elca-matrix.ch>]

Robert Dewar wrote:
> 
> Mats said
> 
> <<Really ? Then show me an example where you think it's reasonable to have
>    a < b not equivalent to b > a
> or
>    a <= b not equivalent to a < b or a = b>>
> 
> Well equivalent is a tricky word, Mats I certainly hope you realize that
> with standard Ada floating-point semantics, you are not guaranteed that
> these pairs of possibilities wll generate identical boolean results!

Yes, I do. But given good definitions of "=" and "<" for a floating
point type, applying my definitions will yield ">", "<=" and "<=" that
are just as good. Defining "good" here is tricky, e.g. you are not
supposed to use "=" for floating point, but rather something like
   abs (a - b) < epsilon * (abs a + abs b)

> I can also easily see someone defining > or <= to mean something completely
> different from comparison on a type for which comparisons make no sense
> (For example <= looks a bit like an assignment ..._

... if opertors could be procedures, or functions could have parameter
modes other than in, but that happens not to be the case. Ada has quite
a conservative philosophy on operator redefinition, why not stick to it
?