From: Steve Gunnell <[EMAIL PROTECTED]>
Date: Sun, 08 Jan 2006 15:02:37 +0800
Hi,
I'm sitting here thinking about cross language calls and what I don't
see anywhere is a prohibition that stops a context from popping a
handler or action or whatever that it didn't place there.
Is there an intent to prohibit or restrict this kind of behaviour?
Yes, indeed. In fact, this is more or less a requirement of the
existing implementation. It is not always strictly enforced (see my
"[PATCH] Restrict clear_eh to handlers in the current context" message
of a few days ago), but the intent is to make it so.
It also seems to me that with coroutines and threads you might have
diverging contexts with different active exceptions and actions.
I am assuming the ithreads model, where there is no sharing of contexts
between threads. I believe that is how threads are currently
implemented in Parrot . . .
So is a stack the correct model for this or are we talking a
hierarchical chain of contexts each with a stack.
Yes, it is not strictly a stack, as contexts can have multiple active
calls. (The term "spaghetti stack" comes to mind.) Part II of the
design will cover this in more detail. But again, this is already a
feature of the current implementation.
Sort of like the user stack I guess.
Cheers,
Steve Gunnell
Actually, I would have assumed that the user stack operated more or less
independently of the call chain, but I see it is kept in the context
structure and not the interpreter. Hmmm . . .
-- Bob
