Gimme some ido... everywhere! This package replaces stock emacs completion with ido completion wherever it is possible to do so without breaking things.
Get it from MELPA: https://stable.melpa.org/#/ido-ubiquitous
Long-time users should know that ido-ubiquitous version 3.0 is a major
update, including a split into two packages, and some of the
configuration options have changed in non-backwards-compatible ways.
If you have customized any options ido-ubiquitous, be sure to check
out M-x customize-group ido-ubiquitous
and M-x customize-group ido-completing-read+
after updating to 3.0 and make sure the new
settings are to your liking.
If you are using this package, you probably want to enable ido
everywhere that it is possible to do so. Here are all the places to
enable ido that I'm aware of. (Note that most of these variables can
also be set via M-x customize-variable
if you prefer that.)
First, enable ido-mode
and ido-everywhere
.
(ido-mode 1)
(ido-everywhere 1)
Install this package from MELPA
and then turn on ido-ubiquitous-mode
:
(require 'ido-ubiquitous)
(ido-ubiquitous-mode 1)
Smex allows you to use ido for completion of commands in M-x, with enhancements like putting your most-used commands at the front of the list. First install the smex package, then follow the directions to set up key-bindings for it.
If you want to use ido for yes-or-no questions, even though it's massive overkill, install my ido-yes-or-no package from MELPA, and then enable the mode:
(require 'ido-yes-or-no)
(ido-yes-or-no-mode 1)
Some commands, such as describe-face
, use completing-read-multiple
instead of completing-read
. You can get ido completion for these
commands with crm-custom-mode
, which replaces
completing-read-multiple
with repeated calls to completing-read
,
which would then use ido thanks to ido-ubiquitous-mode. First, install
the crm-custom
package from MELPA, then enable the
mode:
(require 'crm-custom)
(crm-custom-mode 1)
Remember that when using this mode, completion for affected commands will continue to read additional items until you use C-j to enter an empty input, which terminates the completion. (Due to this quirk, I do not find this mode to be very useful in conjunction with ido, but it does work.)
Lastly, some packages already provide their own interfaces to ido, so ido-ubiquitous specifically avoids interfering with these. If you use any of the following packages, you need to enable ido for each of them separately.
- Magit:
(setq magit-completing-read-function 'magit-ido-completing-read)
- Gnus:
(setq gnus-completing-read-function 'gnus-ido-completing-read)
(You can also use M-x customize-variable
to set all of these
options.)
How does ido-ubiquitous decide when to replace completing-read
?
Why don't some commands use ido completion?
Emacs' completing-read
is a complex function with many advanced
features and some quirks that are only maintained for backwards
compatibility. Not all of these features are supported by ido, so it
is impossible to always replace completing-read
with ido completion.
Trying to use ido when these features are requested can completely
break the completion system. So, by default ido-ubiquitous tries to
get out of the way whenever it detects that these features might be
used by a given call to completing-read
. Furthermore, it's not
always possible to detect based on the arguments to completing-read
whether such ido-incompatible features are being used or not.
ido-ubiquitous uses a series of heuristics to determine whether
unsupported features might be used, and also supports an override
feature to correct it when the heuristics get things wrong.
Each time a function invokes completing-read
, ido-ubiquitous selects
one of 3 modes:
enable
: use ido completion;enable-old
: use ido completion, but with a compatibility fix for old-style default selection; anddisable
: no ido completion.
The following describes in detail how ido-ubiquitous selects the appropriate mode, and what to do when you think it is making the wrong choice.
Ido can get slow on very large collections, so by default ido-ubiquitous disables itself for collections with more than 30,000 items in them. This rule takes precedence over anything else, even overrides that explicitly enable ido completion for a command.
You can change the large collection threshold by customizing
ido-cr+-max-items
.
One feature of completing-read
is that the collection argument can
be a function. This function could simply return a list of all
possible completions, in which case it would be safe to use ido, or it
could implement a completely new completion system, in which case
using ido would interfere with this new completion system (for an
example of this, see the tmm
command). But ido-ubiquitous cannot
tell by looking at the function which kind it is, so it errs on the
side of caution and disables itself whenever the collection is a
function, unless an override exists telling it that the command is
safe for ido completion. You can turn off this safeguard by
customizing ido-ubiquitous-allow-on-functional-collection
. Be aware
that enabling this will likely break completion entirely in any
command that uses this feature to implement non-standard completion.
If you run across a command that unexpectedly uses normal Emacs completion instead of ido completion, it's likely that either this or the previous option is to blame.
If ido-ubiquitous is not running for a command where is should be due
to the functional collection rule, you can add an override for that
command by using M-x customize-variable ido-ubiquitous-command-overrides
. Conversely, if ido completion
causes problems for a command, you can also use this to disable
ido-ubiquitous for that command.
The enable-old
mode of operation is required because the old way for
completing-read
to indicate that the user simply pressed RET and
selected the default option was to return an empty string. When this
old-style mode is used, completing-read
doesn't even know what the
default is supposed to be -- the calling code handles all of that.
But in ido, simply pressing RET will return the first item of the
list, not an empty string. The way to enter an empty string in ido is
C-j. The enable-old
mode enables ido completion, but swaps the
meaning of C-j and RET if you haven't entered any text or cycled the
options yet (once you do either of those, C-j and RET regain their
standard meanings). This allows you to select the default by pressing
RET as soon as the completion prompt appears, as intended (C-j would
select the first item).
Unfortunately, there is no way for ido-ubiquitous to detect when a
command is using this old-style default selection, so instead it uses
a built-in set of overrides telling it about commands that are known
to use old-style defaults. If you discover a command where pressing
RET or C-j at an empty prompt is not doing what you expect it to,
there's a good chance that you need to add an enable-old
override
for that command to ido-ubiquitous-command-overrides
. Luckily, since
this is an obsolete usage pattern, it is unlikely that any Elisp
functions written since 1990 or so will need to be added to this list.
Hopefully all uses of old-style completion will eventually be
eliminated, and with them, the need for this feature of
ido-ubiquitous.
First, invoke the ido-ubiquitous-debug-mode
and ido-cr+-debug-mode
commands. Then, with these two modes active, run the command(s) that
you are having trouble with, and when the completion prompt appears,
make a selection to complete the process. Then, examine the Messages
buffer, where ido-ubiquitous will explain which mode of operation it
selected and why. Based on this, you can add an override to
ido-ubiquitous-command-overrides
. If you are not familiar with the
structure of this variable, I recommend using M-x customize-variable
to edit it, which will help you get it right. If ido completion was
skipped ido completion because the collection was too large, try
giving ico-cr+-max-items
a larger value, or set it to nil if your
computer is fast enough to handle any size of collection.
Updates to ido-ubiquitous often include new overrides, but Emacs will
not edit your override variables if you have already customized them.
So, if you have recently upgraded ido-ubiquitous, remember to invoke
ido-ubiquitous-restore-default-overrides
to add in any new
overrides. (In the future, this process may become automatic:
DarwinAwardWinner#90)
If you end up adding any overrides, please also report them at https://github.com/DarwinAwardWinner/ido-ubiquitous/issues so I can incorporate them into the defaults for future versions. You can also report any bugs you find in ido-ubiquitous.
I've gotten numerous reports about nonsensical warnings produced by
ido-ubiquitous, such as "free variable" warnings about variables that
are most definitely properly declared, or warnings that only appear
when ido-ubiquitous is loaded after another unrelated package. For
many of these warnings, I've never been able to discover the cause or
reproduce the warnings myself, and I've given up trying to figure it
out. Please don't report any new bugs about variable warnings unless
you can tell me how to consistently reproduce them starting from
emacs -Q
. If you are an Emacs expert who knows how to fix these
warnings, please let me know.
You can see the bug reports about weird warnings here.
All users should just use the master branch, or better yet, install from MELPA. The bleeding-edge branch is where I test experimental and unfinished features. Because ido-ubiquitous hooks deeply into the bowels of Emacs, a bug in ido-ubiquitous could easily freeze or crash Emacs entirely. Additionally, some bug only show up when ido-ubiquitous is installed and compiled as a package. So I test every new feature myself for some time on this branch before pushing to the master branch. If you report a bug, I might develop a fix for it on the bleeding edge branch and ask then you to try this branch. Otherwise, normal users don't need to think about this branch.
As of version 3.0, most of the core functionality of ido-ubiquitous
has been spun off into a separate library called ido-completing-read+,
or "ido-cr+" for short. ido-cr+ incorporates all the features of
ido-ubiquitous that are actually just generic improvements to ido that
should probably always be enabled. It implements these fixes in a
single function ido-completing-read+
, which should be suitable as a
drop-in replacement for either ido-completing-read
or
completing-read
. Notably, unlike the original ido-completing-read
,
ido-completing-read+
should always do something useful, by falling
back to normal completion when ido completion won't work.
Additionally, it allows you to manually fall back using C-f and C-b,
in the same way you can use those keys to switch between file and
buffer completion in ido. As a user, you don't really need to know
anything about ido-cr+. However, if you are writing an Emacs package
and would like to incorporate ido completion, you may wish to use
ido-cr+ to get more robust completion with fewer weird edge cases.