Re: gnus-registry: alist-to-hashtable, hashtable-to-alist

[Ted Zlatanov <tzz@lifelogs.com>]

On 28 Sep 2006, reinersteib+gmane@imap.cc wrote:

> [ Digging up a very old message.  Therefore Cc-ing involved people.... ]
>
> On Mon, Feb 24 2003, Andreas Fuchs wrote:
>
>> Today, Ted Zlatanov <tzz@lifelogs.com> wrote:
>>> Could something like hashtable-to-alist-string and
>>> hashtable-from-alist-string be added to the Gnus core?  It would make
>>> my life easier, and I'm definitely not the person to write reliable
>>> versions of these functions :)  
>>
>> Me neither, but will these help:
> ^^^^^^^^^^^^ ???
>
> Who actually wrote these functions?  ChangeLog.2 says:
>
> ,----[ ChangeLog.2 ]
> | 2003-03-28  Teodor Zlatanov  <tzz@lifelogs.com>
> | 
> | 	[...]
> | 
> | 	* gnus-registry.el (gnus-registry-translate-to-alist)
> | 	(gnus-registry-translate-from-alist, alist-to-hashtable)
> | 	(hashtable-to-alist): new functions
> | 	(gnus-register-spool-action): add a spool item to the registry
> `----
>
> If Andreas wrote them, it should have been documented it in the
> ChangeLog as follows:
>
> ,----
> | 2003-03-28  Andreas Fuchs  <asf@void.at>
> | 
> | * gnus-registry.el (alist-to-hashtable, hashtable-to-alist): New
> | 	functions.
> `----
>
> (Andreas has papers on file, so no need to think about "tiny change").
> If Andreas didn't write them, we need to know where they came from.
>
> We really must be more careful about these issues!

I guess it was my mistake.  Sorry.

> Later these were moved to gnus-util.el and Romain added the following
> comment:
>
> ,----[ gnus-util.el ]
> | ;; The following two functions are used in gnus-registry.
> | ;; They were contributed by Andreas Fuchs <asf@void.at>.
> `----
>
> ,----[ ChangeLog ]
> | 2006-04-13  Romain Francoise  <romain@orebokech.com>
> | 
> | * gnus-util.el (gnus-alist-to-hashtable, gnus-hashtable-to-alist):
> | 	Moved here (and renamed) from gnus-registry.el.
> |
> | 	* gnus-registry.el: Require gnus-util.
> | 	Use `gnus-alist-to-hashtable' and `gnus-hashtable-to-alist'.
> `----
>
> [ I'd like to put this change in v5-10 as well, because Gnus functions
> should use the "gnus-" prefix. ]
>
>> (defun alist-to-hashtable (alist)
>> "Build a hashtable from the values in ALIST."
>> (let ((ht (make-hash-table)))
>> (mapc
>> (lambda (kv-pair)
>> (puthash (car kv-pair) (cdr kv-pair) ht))
>> alist)
>> ht))
>>
>> (defun hashtable-to-alist (hash)
>> "Build an alist from the values in HASH."
>> (let ((list nil))
>> (maphash
>> (lambda (key value)
>> (setq list (cons (cons key value) list))))))
>
> [ The current code in gnus-utils.el looks slightly different (see
> rev. 6.7): ]
> @@ -1,16 +1,21 @@
> -(defun alist-to-hashtable (alist)
> +;; The following two functions are used in gnus-registry.
> +;; They were contributed by Andreas Fuchs <asf@void.at>.
> +(defun gnus-alist-to-hashtable (alist)
> "Build a hashtable from the values in ALIST."
> -  (let ((ht (make-hash-table)))
> +  (let ((ht (make-hash-table
> +            :size 4096
> +            :test 'equal)))
> (mapc
> (lambda (kv-pair)
> (puthash (car kv-pair) (cdr kv-pair) ht))
> alist)
> ht))
>
> -(defun hashtable-to-alist (hash)
> +(defun gnus-hashtable-to-alist (hash)
> "Build an alist from the values in HASH."
> (let ((list nil))
> (maphash
> (lambda (key value)
> -       (setq list (cons (cons key value) list))))))
> -
> +       (setq list (cons (cons key value) list)))
> +     hash)
> +    list))

The newer version of gnus-hashtable-to-alist is correct.  The older
version is, I think, broken (maphash is called with a nil argument).

gnus-alist-to-hashtable is also better in the newer version.

I'm OK with all these changes, backported into 5.10 as well.  I
intended to revise and document gnus-registry.el in addition to
working on spam.el again, but my second child born 3 months ago has
made my free time very scarce.  If someone wants to pick up
maintenance of either gnus-registry.el or spam.el, they are welcome to
it--otherwise I'll continue to support them as time allows.

Thanks
Ted