[Openmcl-devel] Is it safe to make hash tables with non-standard tests?

[Tom Emerson]

You don't need to: using 'equal as your test achieves the same result.

Welcome to Clozure Common Lisp Version 1.9-r15757  (LinuxX8664)!
? (defvar foo (make-hash-table :test 'equal))
#<HASH-TABLE :TEST EQUAL size 0/60 #x3020006F2C3D>
? (setf (gethash "abc" foo) 100)
100
? (gethash "abc" foo)
100
T
? (gethash "ABC" foo)
NIL
NIL

If instead you want the test to be string-equal then use 'equalp

? (setq foo (make-hash-table :test 'equalp))
#<HASH-TABLE :TEST EQUALP size 0/60 #x3020006F9D5D>
? (setf (gethash "abc" foo) 100)
100
? (gethash "abc" foo)
100
T
? (gethash "ABC" foo)
100
T

This is portable: same results in SBCL.



On Sun, Jul 14, 2013 at 3:53 PM, Ron Garret <ron at flownet.com> wrote:

> I need a string= hash table, which is not in the standard.  It appears
> that CCL can actually make one:
>
> (make-hash-table :test 'string= :hash-function 'sxhash)
>
> This seems to do the Right Thing, but  it's not documented.  Is it safe to
> use this feature?
>
> rg
>
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-- 
Tom Emerson
tremerson at gmail.com
http://www.dreamersrealm.net/tree
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