digitalmars.D - Proof of concept/proposal: reference counted closures/delegates
Jakob Ovrum <jakobovrum gmail.com> writes:
I wrote a proof of concept that explores how we could support fully featured reference counted closures: https://gist.github.com/JakobOvrum/69e64d82bcfed4c114a5 The proof_of_concept code path is just to show that the `scope` trick works. The with_new_trait code path proposes a new trait __traits(upvalues, func) which takes an alias to a function and returns an alias sequence describing the function's upvalues: (T1, ptrdiff_t offset1, T2, ptrdiff_t offset2, ...) Where each pair is the type of the upvalue and the upvalue's offset in bytes from the context pointer, which can be negative. This trait allows the library code to properly postblit and destroy upvalues, as well as being a reliable way to get the required size of the closure. The benefit of this approach is that it should work as a drop-in replacement for delegates, whether they're nested/anonymous functions or member functions. One difference from delegates is that conversion between functions of different attributes has to be explicit (with the constructor and opAssign). It shares the downside with delegates that upvalues aren't packed together, so while the proposed trait *can* be used to make C++-style value-type closures, they would carry junk in between the upvalues. As for the example implementation, I have more ideas to improve it, particularly regarding attribute propagation and code bloat elimination, but I'd rather do that if the new trait is implemented. Any thoughts?
Nov 10 2015
Dominikus Dittes Scherkl <Dominikus.Scherkl continental-corporation.com> writes:
On Wednesday, 11 November 2015 at 01:27:46 UTC, Jakob Ovrum wrote:Any thoughts?Cool!
Nov 11 2015