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bug#45539: 26.3; `add-to-ordered-list': Add optional arg for :test predi
From: |
Drew Adams |
Subject: |
bug#45539: 26.3; `add-to-ordered-list': Add optional arg for :test predicate for hash table |
Date: |
Thu, 31 Dec 2020 08:40:00 -0800 (PST) |
I just now noticed the doc for this function in (elisp)
`List Variables'. Should have looked in that manual
sooner. (I didn't expect it to be documented there;
never heard of this function before.)
That description confirms what I've said, I think.
Dunno why this function was added (and documented in
the manual, which is usually done only for important
functions). Dunno if anyone uses it.
___
One thing that I've said isn't quite correct: the
list _can_ have duplicates for elements that are
added with no ORDER. IOW, I should have said that
elements that are recorded in the hash table can't
be duplicated (because a hash table has unique keys).
But other elements can be duplicated.
___
If we're adding a TEST optional arg, to accommodate
hash-table and list membership checks, maybe we should
allow callers to specify a :key arg as well. In that
case, instead of adding optional TEST and KEY args we
would presumably want to use `cl-defun' and allow
keyword args :test and :key.
What do you think? I realize that this now is about
redesigning this function a bit, and we (I, at least)
have little knowledge of why this function was added.
Still, it seems like its basic purpose would benefit
from letting you use different :key as well as :test.
___
Until I discovered that the function was in the manual
I was wondering, since this function seems so messed up
and unclear, if we should just remove it. Now I think
we should maybe just fix it by using `cl-defun'.
Another thing (maybe even the main thing) that's
confusing about this function is its name.
This function is about a special kind of ordering:
the "order" you specify for an element is more of a
kind of "score". It doesn't directly reflect
(correspond to) the list position of an element.
And the function is not so much about adding an
an element to a list as it is recording the score of
an element (a score used to determine its order in the
list). And besides the function being able to record
such a score for an element, it can also _remove_ its
score. (So it's not even necessarily about "adding"
a score.
___
Googling for this function (which is how I accidentally
came across it in the Elisp manual), I see that others
have been confused by its behavior and (IIUC) its aim.
E.g.:
https://stackoverflow.com/q/22440069/729907
I've added an answer to that question here, to clarify
some of its confusion.
https://stackoverflow.com/a/65523104/729907
And I've added a clarification answer to the emacs.SE
question (which provoked this bug report), as well:
https://emacs.stackexchange.com/a/62542/105
- bug#45539: 26.3; `add-to-ordered-list': Add optional arg for :test predicate for hash table, Drew Adams, 2020/12/29
- bug#45539: 26.3; `add-to-ordered-list': Add optional arg for :test predicate for hash table, Lars Ingebrigtsen, 2020/12/29
- bug#45539: 26.3; `add-to-ordered-list': Add optional arg for :test predicate for hash table, Drew Adams, 2020/12/30
- bug#45539: 26.3; `add-to-ordered-list': Add optional arg for :test predicate for hash table, Lars Ingebrigtsen, 2020/12/30
- bug#45539: 26.3; `add-to-ordered-list': Add optional arg for :test predicate for hash table, Drew Adams, 2020/12/30
- bug#45539: 26.3; `add-to-ordered-list': Add optional arg for :test predicate for hash table, Drew Adams, 2020/12/30
- bug#45539: 26.3; `add-to-ordered-list': Add optional arg for :test predicate for hash table, Lars Ingebrigtsen, 2020/12/30
- bug#45539: 26.3; `add-to-ordered-list': Add optional arg for :test predicate for hash table, Lars Ingebrigtsen, 2020/12/30
- bug#45539: 26.3; `add-to-ordered-list': Add optional arg for :test predicate for hash table, Drew Adams, 2020/12/31
- bug#45539: 26.3; `add-to-ordered-list': Add optional arg for :test predicate for hash table,
Drew Adams <=
- bug#45539: 26.3; `add-to-ordered-list': Add optional arg for :test predicate for hash table, Drew Adams, 2020/12/31