On Saturday, 26 July 2014 at 10:49:25 UTC, Marc Schütz wrote:
Interesting proposal. It seems that you want to change the
default for pointers in D, but Walter will probably not like
that ;-). But I wonder how much language support this actually
needs, much of it seems implementable with templates, which is
probably much more acceptable.
What language interface should be provided for RC is up to
debate. Getting it working at the binary level is problematic
enough, so I focused on it.
Some random comments:
Scoped: "The reference count is incremented when escaped or
copied to a fat pointer."
Could you explain that? A scoped pointer can by definition
never be escaped; therefore there should be no need to pass the
reference counter along.
Disallowing escaping of scoped parameters implies strict scoping
can work. I was trying to get escaping working. It's easy to deny
it if the need be.
Function parameters: "Caller doesn't increment the counter
when passing a pointer as a function argument."
There are some corner cases here. For example when an r-value
is moved into a function as an argument. The callee will not
decrement the RC of its parameters, with the consequence that
the RC never goes to 0. There might be other problems, in
particular in the presence of optimizations.
Ouch, probably there is the same problem with tail call
optimization. As of now, I was trying to get sharing and casting
work, protocol for function parameters needs more work, will
think about conservative counting here.
See also my writeup on borrowing, will add more examples there:
http://wiki.dlang.org/User:Schuetzm/scope
Hmm, if you got strict scoping work, that will be interesting.
