On 7/25/2014 8:41 PM, Manu via Digitalmars-d wrote:
No, because there's no obvious reason to define opEquals if you do define opCmp
and the opEquals would be the same.
It seems to me, at face value, that opCmp is for full range of comparisons, and
opEquals is for unordered types. Surely this is a reasonable conclusion to make?
I don't see how you can say that a compiler generated opEquals in the presence
of a user opCmp can reliably be correct.
You cannot say that opCmp can reliably be used for ==. Andrei provided a more
specific example.
It may be correct, if you're lucky, and that's the best offer you'll get.
opCmp==0 however is practically certain to be correct, since <= and >= are
required to work... and the api embodies the concept of equality, it would be
very hard to write an implementation where equal was broken, but <,<=,>=,> all
worked.
At this point, it's obvious we are going around in a circle. You ask the same
questions over and over, and I answer them over and over. If you don't want to
accept that equality and comparison are fundamentally different operations, I
can only repeat saying the same things.
