[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: issue QUOTE-SEMANTICS, version 2
- To: Sandra J Loosemore <email@example.com>
- Subject: Re: issue QUOTE-SEMANTICS, version 2
- From: David A. Moon <Moon@STONY-BROOK.SCRC.Symbolics.COM>
- Date: Fri, 17 Mar 89 18:55 EST
- Cc: firstname.lastname@example.org
- In-reply-to: <8903172048.AA07042@defun.utah.edu>
Date: Fri, 17 Mar 89 13:48:43 MST
From: email@example.com (Sandra J Loosemore)
> Date: Tue, 14 Mar 89 19:48 EST
> From: David A. Moon <Moon@STONY-BROOK.SCRC.Symbolics.COM>
> I can't support either of the other two proposals because they use
> the words "copying" and "coalescing" without defining their meaning.
"Copying" means making an equivalent object that is similar as a
constant, but not necessarily EQL, to the original.
OK, but the proposal needs to be updated to say that, since I want
to base my vote only on what proposals actually say.
I now have a question of my own about how proposal
COPYING-ALLOWED-BUT-NO-CONSTRAINTS interacts with issue
CONSTANT-COMPILABLE-TYPES. Maybe somebody who supports this
issue can help clarify this.
On types where the notion of "similar as a constant" is left
unspecified (for example, readtables), do you want this proposal to
mean that copying is entirely forbidden, or that if the implementation
has defined some behavior for "similar as a constant" on that type,
that it can go ahead and copy?
I don't think I'm the one you were expecting a reply from, but if I
have to guess, I think it's the latter. If an implementation is allowed
to extend "similar as a constant", then copying is consistent with the
definition of "similar as a constant" actually in force in that
implementation, not with the book definition.
If copying is entirely forbidden in such a case, the implementation
cost for this proposal will be just as high as for proposal NO-COPYING.
Does this mean that as long as there is one data type for which copying
is forbidden, perhaps some user-defined data type, there is no implementation
advantage of COPYING-ALLOWED-BUT-NO-CONSTRAINTS over NO-COPYING?
If so, that would seem to knock COPYING-ALLOWED-BUT-NO-CONSTRAINTS
pretty completely out of the running.