On 7/25/2014 1:47 PM, H. S. Teoh via Digitalmars-d wrote:
On Fri, Jul 25, 2014 at 06:56:40PM +0000, Jonathan M Davis via Digitalmars-d
wrote:
[...]
So, if we remove the new check for a user-defined opEquals when opCmp
is defined, then you don't have to define opEquals.
This is even worse, since it may silently introduce runtime breakage.
The original type may have had opCmp defined just so it can be used with
AA's, and now after the upgrade to 2.066, suddenly the custom opCmp code
they wrote specifically to work with AA's doesn't get used anymore, yet
the compiler silently accepts the code, and the problem won't be found
until runtime.
Once again,
"The thing is, either this suffers from == behaving differently than AAs, or
you've made opEquals superfluous by defining it to be opCmp==0. The latter is a
mistake, as Andrei has pointed out, as opCmp may not have a concept of equality,
and opEquals may not have a concept of ordering.
I.e. it's not just about AAs."
What you're defending is code of this sort running without error:
S[T] aa;
S s;
aa[t] = s;
assert(s != aa[t]);
Which IMO fits the D motto of being correct first, and performant if you
ask for it.
See the above snippet.
