On Fri, Dec 08, 2006 at 05:05:00PM -0500, Matt Diephouse wrote: > Patrick R. Michaud <[EMAIL PROTECTED]> wrote: > >Does anyone have any suggestions about what sort of PIR > >code and/or PMCs we need to be able to do make the following > >Perl 6 code work...? > > Sure. I think Tcl handles this pretty nicely at the moment (although > Leo disagrees - he likes the Ref PMC route). The main idea is that > aliasing/binding enters the same PMC under a different name and that > assignment morphs the PMC.
Does this basically assume that every PMC knows how to morph into any other type? (In the example I gave the PMC would need to be able to morph from an integer to a list, but in the general case it could be converting to any type.) > With this scheme, you'd have to use assign in this last case instead > of set (with a morph to really make it safe) because you need to reuse > the same PMC: > > #### @a[4] = [1, 2] > $P2 = 'list'(1, 2) > find_lex $P3, '@a' > $P3 = $P3[4] > morph $P3, .Undef > assign $P3, $P2 > > If you're only assigning your own PMCs, you can drop the morph (which > isn't technically safe anyway). I don't think I can assume I'm only assigning my own PMCs. (This is being handled in PAST-pm, and so it probably needs to work with PMCs in general.) And I know that morphing isn't safe, which is why I've been avoiding it. Hmm... perhaps what we really need is an opcode or sequence of opcodes that convert a PMC into a value-based copy (clone?) of another PMC, but keeping the first PMC as the same PMC so that other references to it will see the new value and type. Pm
