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Issue: HASH-TABLE-ACCESS (version 2)
- To: firstname.lastname@example.org
- Subject: Issue: HASH-TABLE-ACCESS (version 2)
- From: vanroggen%aitg.DEC@decwrl.dec.com
- Date: Thu, 13 Oct 88 12:30:44 PDT
References: hash-tables (Chapter 21 of CLtL)
Edit History: 13-Sept-88, version 1 by Walter van Roggen
13-Oct-88, version 2 by Walter van Roggen
There are many characteristics of hash-tables which are specified upon
creation but are not accessible afterwards.
Add the following functions to the language:
Returns the current rehash size of a hash table.
Returns the current rehash threshold of a hash table.
Returns the current size of a hash table.
Returns the test used for comparing keys in the hash table.
By default the value will be EQL.
VAX LISP and Lucid 3.0 implement the proposal.
Cost to Implementors:
Most of these should be trivial to implement, since the information
must be present for nearly all types.
Cost to Users:
None. This is an upward-compatible extension.
Cost of Non-Adoption:
The benefits would not be available in a portable fashion.
Programs would be able to access useful information otherwise hidden.
For example, it would allow programs to gain statistics about hash
table usage that might enable better tuning.
None of these are required to be SETF'able, though some might be
reasonable implementation-dependent extensions. Including such
modification abilities might constrain some implementations unduly.
This first appeared in ">GLS>clarifications.text" of 12/06/85.