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
Version 3.0 changes
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
M-x customize-group ido-ubiquitous and
ido-completing-read+ after updating to 3.0 and make sure the new
settings are to your liking.
How to enable ido in as many places as possible
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.)
(ido-mode 1) (ido-everywhere 1)
ido-ubiquitous (this package)
Install this package from MELPA
and then turn on
(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)
describe-face and certain other commands
Some commands, such as
completing-read. You can get ido completion for these
crm-custom-mode, which replaces
completing-read-multiple with repeated calls to
which would then use ido thanks to ido-ubiquitous-mode. First, install
package from MELPA, then enable the
(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.)
Packages with built-in ido support
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.
(setq magit-completing-read-function 'magit-ido-completing-read)
(setq gnus-completing-read-function 'gnus-ido-completing-read)
(You can also use
M-x customize-variable to set all of these
Frequently asked questions
How does ido-ubiquitous decide when to replace
Why don't some commands use ido completion?
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
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; and
disable: 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.
Disabling ido completion when the collection is very large
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
Disabling ido completion when the collection is a function
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
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.
Disabling or enabling ido completion by overrides
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
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.
What is old-style default selection?
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
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
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
How can I troubleshoot when ido-ubiquitous isn't doing what I want?
First, invoke the
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
to edit it, which will help you get it right. If ido completion was
skipped ido completion because the collection was too large, try
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:
Where can I report bugs or suggest new overrides?
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'm getting some weird warnings from ido-ubiquitous when Emacs starts.
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.
What is the "bleeding-edge" branch?
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
ido-completing-read+, which should be suitable as a
drop-in replacement for either
completing-read. Notably, unlike the original
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.