On Thu, 1 Aug 2002, Melvin Smith wrote: > Jerome Vouillon writes: > >On Wed, Jul 31, 2002 at 11:22:56PM -0400, Melvin Smith wrote: > >> And they need to be COW, as closures have access to their > >> own copies of lexicals. I asked Jonathan to reuse the stack code > >> I had already written because it was using the same semantics > >> with COW as control and user stacks. > > > >I'm confused here. In Jonathan's code, the stack is COW, not the > >scratchpads. If instead of using stacks you make each scratchpad > >contains a pointer to its parent, there is no need to copy anything: > >several scratchpads can then share the same parent. > > 1) Our stacks are being reworked to be tree-based, so multiple children > can point to the same parent.
COW is a win when you may be able to avoid copying large amounts of data. In a world of 4-character indents and 80-column editor windows, I'm not sure the extra machinery of COW is a win -- an immediate copy of a stack 3 or 4 deep will be fast, and won't take much memory. /s
