Dan Sugalski <[EMAIL PROTECTED]> writes: > At 11:19 PM +0200 6/29/03, Leopold Toetsch wrote: >>Dan Sugalski wrote: >>> ... I'd also like to be able to manipulate the stacks in a context, >>> pushing things on them, changing values on them, and generally >>> messing about with the things, so I'm all for it. >> >> Do you have some examples for a usage of such manipulations? I >> thought that a return continuations should exactly match the state >> of the caller, so that the C<updatecc> op would do the work. >>But there are for sure some hacks, that might need some: >> >> updatecc <.stack> <.action> item > > Yep, that could work. > > There are a few actual good reasons to do this: > > *) A subroutine may want to affect the warnings state of its caller > *) A sub may want to add in block exit actions (though that's more an > inspection for the block exit item on the caller's stack) > *) It's possible the callee may want to mess around with an exception > handler at an outer level, though that's probably a bad idea > *) The callee may want to insert elements onto the control stack of > the caller > > Not *very* good reasons, mind, but... :)
Yeah, but at least one of 'em is required in Perl 6 (the 'affect the warnings state of the caller' thing) isn't it? -- Piers
