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- To: CL-Cleanup@SAIL.Stanford.EDU
- Subject: Issue: DYNAMIC-EXTENT
- From: Kent M Pitman <KMP@STONY-BROOK.SCRC.Symbolics.COM>
- Date: Tue, 4 Apr 89 14:10 EDT
- Cc: sandra%defun@CS.Utah.EDU
Sandra and Gabriel initially claimed to oppose this even in principle.
However, Steele and I drafted a revised proposal over lunch Thursday.
The text of the revised proposal was:
GLS and KMP 3/30/89
Amendment to DYNAMIC-EXTENT:NEW-DECLARATION
* Strike sentences 3 and 4 of paragraph 1.
* Move paragraphs 3 through n-1 to the examples.
* Strike last paragraph.
* Add this text after paragraph 1:
_Definition_: Object _x_ is an _otherwise_inaccessible_part_ (OIP)
of _y_ iff making _y_ inaccessible would make _x_ inaccessible.
(Note that every object is an OIP of itself.)
Suppose that construct _c_ contains a DYNAMIC-EXTENT declaration
for variable _v_ (which need not be bound by _c_). Consider the
values _w1_, ..., _wN_ taken on by _v_ during the course of some
execution of _c_. The declaration asserts that if object _x_ is
an OIP of _wI_ when _wI_ ever becomes the value of _v_, then
just after execution of _c_ terminates _x_ will be either
inaccessible or still an OIP of _v_.
The proposal was also amended in the meeting to say:
"If the assertion is ever violated, the conseqeuences are undefined."
The fully amended proposal passed 17-0.
It was generally agreed that we would also like to consider a proposal
on dynamic extent functions at the next meeting. (Sandra said she would
prepare one, and has already done so. See issue DYNAMIC-EXTENT-FUNCTION.)