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DECLARE SPECIAL Considered Confusing
- To: Pavel.pa@XEROX.COM
- Subject: DECLARE SPECIAL Considered Confusing
- From: "Scott E. Fahlman" <Fahlman@C.CS.CMU.EDU>
- Date: Sat, 12 Jul 1986 03:19:00 -0000
- Cc: Common-Lisp@SU-AI.ARPA
- In-reply-to: Msg of 11 Jul 1986 21:43-EDT from Pavel.pa at Xerox.COM
- Sender: FAHLMAN@C.CS.CMU.EDU
Thanks for working out a coherent proposal for your proposed changes to
the special declaration scoping rules.
My feeling on this is that any change to the scoping rules is a very big
change: such a change requires a lot of work to fix up existing
implementations, and it has the potential to create a lot of subtle bugs
in existing user code. Maybe in this case it is not quite so serious,
since several implementations are currently incorrect, but still it is a
big alteration in an area that was discussed and settled long ago.
A change of this size should only be made if one of the following
1. The current situation is inconsistent and untenable.
2. The current situation causes serious trouble in practice for
implementors or code writers.
3. We have nearly unanimous agreement that the new way is enough better
that it is worth the trouble to make the change.
I don't see any evidence for 1 or 2, and as of now I don't hear the kind
of enthusiasm for this change that 3 would require. Then again, I
haven't heard any implementors say they absolutely oppose this change.