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functions that return nonstandard extra values
- To: George J. Carrette <GJC@MIT-MC.ARPA>, DCP@SCRC-QUABBIN.ARPA
- Subject: functions that return nonstandard extra values
- From: David C. Plummer <DCP@SCRC-QUABBIN.ARPA>
- Date: Tue, 5 Nov 85 10:34 EST
- Cc: common-lisp@SU-AI.ARPA, AS%hplabs.csnet@CSNET-RELAY.ARPA
- In-reply-to: <[MIT-MC.ARPA].705135.851104.GJC>
Date: Mon, 4 Nov 85 22:00:48 EST
From: "George J. Carrette" <GJC@MIT-MC.ARPA>
On the bright side, the existence of a standard helps system maintainers
to resist users continually asking for changes to the language that
have but minor benefit, such as this gethash thing. With only
a minor change in efficiency the user could store (CONS <key> <value>)
in the hash table, and get what he wanted, the EQ'ified key and
This is no longer a simple hash table, as GETHASH doesn't get the value.
Instead, the user must do (CDR (GETHASH ...)), and MUST do it in all
places. There are other problems with this solution. PUTHASH over an
existing entry will change the key, forcing the user to do a GETHASH
first. This is almost MODIFY-HASH, which is an efficiency item missing
If a user was really interested in efficiency he wouldnt
use the hairy system-provided hash table implementations anyway.
I agree with DLW's reply to this statement.