On Friday, 15 February 2013 at 17:42:30 UTC, Steven Schveighoffer
wrote:
On Fri, 15 Feb 2013 12:11:55 -0500, monarch_dodra
<monarchdo...@gmail.com> wrote:
Also keep in mind that "a < b" is implemented as two calls to
"a.opCmp(b)", and "a.opCmp(b)" is itself usually implemented
as two calls to "something < something else" (!)
Huh?
a < b is implemented as a.opCmp(b) < 0, not two calls to
a.opCmp(b).
Yes. But isn't opCmp still more work than just a<b? It must be
because it returns three states instead of two. So, I think the
general warning on opCmp is warranted especially with structs.
For structs we could use compile time reflection to provide
automatic efficient opCmp behavior. Section 3.1 here outlines a
way:
https://github.com/patefacio/d-help/blob/master/doc/canonical.pdf
Any comments appreciated.
Thanks
Dan
HOWEVER, when you get to the point of executing a == b, it's
implemented as !(a < b) && !(b < a), which could more
efficiently be rewritten as a.opEquals(b) or a.opCmp(b) == 0.
