From: "John M. Dlugosz" <[EMAIL PROTECTED]>
Date: 11 Apr 2008 20:12:41 -0000
. . .
What happens? The OUTER scope no longer exists at CALL 3. Does a
symbolic reference to OUTER require that the entire scope be
retained, just in case? If "OUTER" itself (or OUTER::OUTER::...) is
symbolic, it would need to remember everything always, just in case.
I would assume so. This is no different than the "lexical-then-dynamic"
rule for "goto", which always requires metadata for each label to
identify them to dynamic callers. But, in both cases, it ought to be
possible to do this using static metadata, incurring no runtime penalty.
Yet in CALL 1, the use of OUTER makes sense, and is a normal use.
This situation should be allowed, or you'll have a hard time
describing exactly when OUTER may be used symbolically, since the
simple description now is that all blocks are closures, but most can
be optomized down.
Agreed.
Now look at CALL 2. The situation is similar in that the outer scope
still exists, but it is much harder for OUTER to figure out where to
look. Does this work? If not, again, its hard to explain just when
it should or shouldn't, because cases that do are just automatic
degenerate forms of "every block is a closure".
--John
I don't see that this is any harder; unless I'm misunderstanding you,
this is just another normal closure usage case. The OUTER scope is
always the one defined by outersub, no matter how many calls back in the
dynamic chain it might be.
-- Bob Rogers
http://rgrjr.dyndns.org/
