--- Michael Lazzaro <[EMAIL PROTECTED]> wrote:
>
> How, then, would you design an interface around (Concept 1) -- the
> listener/eventloop/subprocess model? Pseudocode for a top-level
> event
> loop might be something like:
>
> loop {
> sleep($fraction), next
> unless $e = get_event();
>
> process_event($e);
> }
>
What about this:
1. C<yield> always acts the same way -- stores args in CurThread.result
and gives up control to [?something?].
2. Using the keyword (probably function) C<coro> returns a Code object
that when called executes in serial, in the current thread context, and
causes C<yield> to transfer control back to the caller (essentially
call-cc) returning the result from yield.
3. Using the keyword (probably keyword - it's complex) C<thread> spins
off another thread of execution, causing yield to block.
4. Using C<resume> DTRT. In order to support arg-resetting, maybe a
simple call does no-arg-reset, while a resume passes new args. Or vice
versa.
E.g.,
sub fibs(?$a = 0, ?$b = 1) {
loop {
yield $b;
($a, $b) = ($b, $a+$b);
}
}
print fibs; # Error: use of yield without thread or coro context.
print coro fibs; # Coderefs autoderef into calls, right?
print thread fibs; # Magic Thread object treats "FETCH" as "wait".
Continuing:
Anyone can yield, so long as there's two active threads. Just one
thread produces an error/warning/exception/whatever.
Anyone can yield if there's a coro entry on the stack someplace.
If there's two active threads and a coro entry, the nearer (most
recently placed on the stack) wins.
There's an optional arg to yield to override this, as with C<leave>. Or
maybe yield is a method on both the Coroutine and Thread classes.
Either way, it can be made explicit.
Recursing doesn't create a new coro unless you say C<coro>.
Saying C<my &left = coro &_;> is how you create a recursive coro.
-4,-2 s/coro/thread/g
Exampling:
sub traverse(Hash $tree) {
return unless $tree;
traverse $tree{left} if $tree{left};
yield $tree{node};
traverse $tree{right} if $tree{right};
}
my %hash is Tree;
my &cotrav := coro &traverse(%hash);
print $_ for <ctrav.resume>;
my &thtrav := thread &traverse(%hash);
print $_ for <thtrav.resume>;
=Austin
