Bill Baxter Wrote: > On Wed, Oct 14, 2009 at 7:42 AM, Jason House > <jason.james.ho...@gmail.com> wrote: > > Andrei Alexandrescu Wrote: > > > >> Right now we're in trouble with operators: opIndex and opIndexAssign > >> don't seem to be up to snuff because they don't catch operations like > >> > >> a[b] += c; > >> > >> with reasonable expressiveness and efficiency. > > > > I would hope that *= += /= and friends could all be handled efficiently > > with one function written by the programmer. As I see it, there are 3 basic > > steps: > > 1. Look up a value by index > > 2. Mutate the value > > 3. Store the result > > And as Chad J reminds us, same goes for in-place property mutations > like a.b += c. > It's just a matter of accessing .b vs .opIndex(b). And really > same goes for any function a.memfun(b) += c could benefit from the > same thing (a.length(index)+=3 anyone?) > > > it's possible to use opIndex for #1 and opIndexAssign for #3, but that's > > not efficient. #1 and #3 should be part of the same function, but I think > > #2 shouldnot be. What about defining an opIndexOpOpAssign that accepts a > > delegate for #2 and then use compiler magic to specialize/inline it? > > It could also be done using a template thing to inject the "mutate the > value" operation:
The only issue with templates is that they're never virtual
