[TCLCORE] Coroutine puzzler

Hi everyone!

[This is related to a recent c.l.t thread on idioms for generating and
gathering coroutine results, in case you're wondering.]

If I have a coroutine and I want to make the code that invoked me do a
[break], how do I do this? (By "code that invoked me" I mean either the
code that called the [coroutine] command, or the code that called the
coroutine by name by way of resuming from a [yield].)

   % proc all args {
       yield [info coroutine]
       foreach item $args {yield $item}
       return -code break
   }
   % coroutine a all 1 3 5 7
   ::a
   % while 1 {puts x=[a]}
   x=1
   x=3
   x=5
   x=7
   invoked "break" outside of a loop
   % set errorInfo
   invoked "break" outside of a loop
       while executing
   "all 1 3 5 7"
       invoked from within
   "a"
   % info patchlevel
   8.6b3

I've tried a few other alternatives, but I've not found something which
can make that simple [while] terminate once all values have been
retrieved; what am I missing? (Or is this a bug?) My reading of TIP 396
and my memory of the (many many!) arguments around this area is that it
*ought* to work...

Donal (yes, I also want the coroutine to go away at that point, but
that's easy to arrange once I get the [break] out).

begin:vcard
fn:Donal K. Fellows
n:Fellows;Donal
org:The University of Manchester;Research Computing Services
adr:;;Oxford Road;Manchester;;M13 9PL;United Kingdom
email;internet:dona...@manchester.ac.uk
version:2.1
end:vcard

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