On 2/5/14, 4:57 PM, Adam D. Ruppe wrote:
On Thursday, 6 February 2014 at 00:42:20 UTC, Andrei Alexandrescu wrote:
One other school of thought (to which I subscribe) is that one should
take advantage of reference counting where appropriate within a GC
milieu, regardless of more radical RC approaches that may be available.
I agree with that stance, but I don't think there's a blanket rule
there. I think RC freeing small slices will waste more time than it
saves. Large allocations, on the other hand, might be worth it. So
std.file.read for example returns a large block - that's a good
candidate for refcounting since it might be accidentally subject to
false pointers, or sit around too long creating needless memory
pressure, etc.
That sounds reasonable. One possibility would be to define FreshSlice!T
to mean this is a freshly-allocated slice; then it can be converted to a
refcounted one or just a GC one.
Anywho, I'd just go through on a case-by-case basis and tackle the big
fish. Of course, a user could just do scope(exit) GC.free(ret); too.
That won't work because user code can't always know whether something
received from the library had been freshly allocated or not.
Binding ref is also a related topic. All of these are complex matters,
and I think a few simple sketches don't do them justice.
I'd rather discuss these details than adding RCSlice and toGC everywhere
for more cost than benefit.
Have at it, of course. This is not constant sum, just don't hijack this
discussion. I should warn you however we've been discussing this
literally for years; your examples are just scratching the surface.
Andrei
