RE: [External] : Re: Q: Is there a built-in way to read multiple file names?

[Drew Adams <drew.adams@oracle.com>]

> > >> I wish that *completions* buffer allowed selecting
> > >> multiple candidates at once when using
> > >> `completing-read-multiple' or similar commands.
> > >
> > > I think completion is the wrong framework for this
> > > purpose, because the user might want to select
> > > files/buffers/whatever whose names don't share
> > > anything in common.
> >
> > IMHO, helm proves that completion framework can be used for very quick
> > selection. It does it via:
> >
> > 1. The notion of "current" candidate from the list that can be navigated
> >    right from the minibuffer (like next/previous-completion in the
> >    *completions*)
> > 2. minibuffer command to mark/unmark candidates quickly
> > 3. ability to retain marked candidates even the prompt input changes
> >
> > I find it quick and convenient to use, despite being a completion
> > framework.
> >
> > I also do not see why the same cannot be done based on the basis of
> > completion-list-mode.
> 
> The display parts might be suitable for selection, but the entire
> completion machinery behind this makes absolutely no sense for the
> purpose of selection based on attributes that are not names or
> collection of strings.


The Subject line says "built-in".  But it
seems the thread has moved on to talk about
ways that aren't built-in.

In that context, I'll mention Icicles wrt
some things that have been brought up.
(This has been available since 2006.)
____

1. Wrt "marking" files for some action:

Icicles calls this "saving" instead of
"marking" a completion candidate.

The list of file names you chose ("save")
is the value of a variable (by default,
`icicle-saved-completion-candidates').
You can also save them to a file.

. The `<insert>' key saves the "current"
  candidate (e.g., during cycling).
. In *Completions*, `M-S-mouse-2' on a
  candidate saves it.
  Alternatively, `mouse-1' before a
  candidate, then `mouse-3' twice after
  it, saves it.
. `C-M->' saves all candidates.
. `C-M-)' saves the candidates in the
  active region in *Completions*.
. `M-S-mouse-3' in *Completions* saves
  all candidates, or those in the region
  if active.
. `C-M-<' retrieves a set of saved
  candidates at any time, replacing the
  current set of candidates.
. There are also keys to _add to_ a set
  of saved candidates.


2. You can match file content, in addition
to, or instead of, file name.


3. Wrt choosing files according to file
attributes:

One of the variables that controls matching
and filtering is `icicle-file-predicate'.
You can use that to filter candidates that
have certain attribute values.  E.g., this
predicate limits candidates to files whose
size is at least 5000 bytes:

(lambda (f)
  (> (file-attribute-size
       (file-attributes f)) 
     5000)))


4. Wrt choosing (e.g. "marking") a set of
files using different criteria, matching
different name or content patterns, with
different attributes, locations, etc.:

You can use one set of completion criteria
and "save" some candidates based on that,
then change to a different set of criteria
and "save" some more.  You can accumulate
criteria, narrowing a set of matches by
adding another criterion (e.g., additional
name pattern).

You can save sets to different variables.
You can recombine multiple saved sets.
(And then filter that combination, save
from it, etc.)


5. You can mark file names in Dired and
create, or add to, "saved" sets of names
for subsequent use in file-completion
commands (retrieve sets as candidates).
______

You don't NEED to "mark" (save) a set
of file-name candidates to act on them,
of course.  You do that when it makes
sense - in particular, when you're likely
to want to reuse such a set later.
______

Saving and retrieving completion-candidate
sets (file names are one kind of candidate)
is described here:

Quick description:

https://www.emacswiki.org/emacs/Icicles_-_Nutshell_View#ChooseBeforeYouAct

More extensive description:

https://www.emacswiki.org/emacs/Icicles_-_Candidate_Sets