Am Donnerstag, 27. Juli 2006 19:44 schrieb Matt Diephouse: > .sub __get_string :method > $P0 = new .Exception > throw $P0 > .end > > Running this gives: > > caught > No exception to pop.
PIR code running on behalf of a vtable (or MMD) function is implemented by entering a secondary runloop (see src/pmc/delegate.pmc). The C code and the extra runloop is acting as a Continuation barrier. There are also some notes about that in dan's blog. I've experimented some time ago to get at least exceptions working by rewinding runloops also, but have failed so far. There's no way to get full Continuations working around such C code barriers, except by *not* entering secondary runloops at all for these cases[1]. This could be achieved by (optionally) returning a new PC for all vtable/MMD functions that is, by changing the internal (C) calling conventions of all the PMC code. leo [1] we can't avoid that for e.g. custom sort functions, but these are special enough that we could restrict these.
