On Wed, Jun 24, 2009 at 9:32 AM, Lex Spoon<sp...@google.com> wrote:
> It's the *call* of runAsync that the compiler pays direct attention
> to, not its argument. That's why I am pushing back against approaches
> that annotate some aspect of the argument.
I think the push-back is a really good idea. It seems like this is a
tricky thing to get right and it would be a royal pain to redo it.
My personal favourite is option 6, with some caveats. I think, to
make option 6 work, you need the compiler to be able to prove that a
given argument to runAsync is assigned exactly once before passing it
to runAsync, and that it's not reused. I think you can satisfy the
first requirement by requiring that the local is declared final. I
don't know if it's possible to make sure it's not passed to two
different runAsyncs.
So, what I'm saying is this:
// final is required to make sure callback is assigned only once
@SplitPointName("foo")
final AsyncCallback callback = chooseACallback();
GWT.runAsync(callback);
// this should be a compiler error because it's a second split point
with the same callback instance
GWT.runAsync(callback);
The following should be allowed:
@SplitPointName("foo")
final AsyncCallback callback = chooseACallback();
if (flipACoin())
GWT.runAsync(callback);
else
GWT.runAsync(callback);
If it's not possible (or not feasible) to make it a compiler error to
reuse a callback, then I prefer option 4 over option 1, but either
would be fine.
Ian
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