RE: TAB for non-editing modes

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

> Duplication is not a good way to evaluate this, we have many keys that
> are duplicated.

Yes, for this command alone, we have `n', `SPC', `C-n', and `down'.

`C-n' and `down' often go together. `n' is a shortcut for `C-n', since Dired
is read-only.

`SPC' and `DEL' are sometimes used in Emacs (e.g. View, Info) to browse down
and up (forward or back). But in Dired we've broken that, since `DEL'
unmarks entries instead. Same thing for Buffer Menu. I wouldn't mind if
`SPC' removed the current mark and moved down, in analogy with `DEL', but
it's probably too late to change that.

> The question is it useful? Is it intuitive to use? Is it consistent
> with other uses of the same key?  IMO the answer is YES to all those
> questions.

The question is not just whether it useful, but how useful it is. When there
are already umpteen other simple keys bound to a command that is not
particularly important, is it worthwhile to waste another key on it?

Especially a key such as `TAB', which has important associations and uses in
other contexts:

- `TAB' is used for indenting, which can be context-dependent. Someday
perhaps we will have a notion of indenting for Dired. (No idea what such
indentation might mean - perhaps for inserted subdirs?)

- `TAB' is used for completion - both minibuffer and buffer text. Someday
perhaps we will have some notion of "completing" a file or directory entry
in Dired. (No idea what such completion might mean.)

- `TAB' is used for field navigation (particularly outside Emacs), as
Lennart mentioned. Someday perhaps we will have fields of some sort in
Dired.

Maybe you are thinking of a file/directory name in Dired as a field. Perhaps
that's what you think of as "consistent with other uses of the same key". In
that case, it would make sense, but I don't see `TAB' as very helpful for
this in Dired today.

Perhaps if we had a notion of "current column" and various operations were
permitted on the data in the current Dired column (e.g. change file
permissions, change the date), then `TAB' could move to the next "field" in
the current column. IOW, if a user changed the current column to
`Permissions', then `TAB' would move to the next `Permissions' field, where
you could change a permission (other than by `M', which acts regardless of
the current cursor column).

I'm not familiar with wdired, but perhaps it has such a notion of field, so
that some editing commands get their specific effect from the kind of field
the cursor is in. I don't know. In that case, letting `TAB' move among
fields might be useful.

Anyway, this is not all that important. I just don't like to see good keys
wasted.