Re: gnus-completing-read vs XEmacs 21.4

[Dave Goldberg <david.goldberg6@verizon.net>]

> This is almost certainly because old (for some value of old)
> versions of Emacs and XEmacs expect the second value of
> try-completion to be an alist and the car of each element is
> checked for matching.

[...]

I'm running 21.4 (patch 22) "Instant Classic" XEmacs Lucid which I understand is current stable.  The doc string for try-completion says

`try-completion' is a built-in function
(try-completion STRING COLLECTION &optional PREDICATE)

Documentation:
Return common substring of all completions of STRING in COLLECTION.
COLLECTION must be an alist, an obarray, or a function.
Each string in COLLECTION is tested to see if it begins with STRING.
All that match are compared together; the longest initial sequence
common to all matches is returned as a string.  If there is no match
at all, nil is returned.  For an exact match, t is returned.

If COLLECTION is an alist, the cars of the elements of the alist
(which must be strings) form the set of possible completions.

If COLLECTION is an obarray, the names of all symbols in the obarray
are the possible completions.

If COLLECTION is a function, it is called with three arguments: the
values STRING, PREDICATE and nil.  Whatever it returns becomes the
value of `try-completion'.

If optional third argument PREDICATE is non-nil, it is used to test
each possible match.  The match is a candidate only if PREDICATE
returns non-nil.  The argument given to PREDICATE is the alist element
or the symbol from the obarray.

-- 
Dave Goldberg
david.goldberg6@verizon.net