emacs/doc/misc/ido.texi

\input texinfo    @c -*-texinfo-*-
@setfilename ../../info/ido
@settitle Interactive Do
@include emacsver.texi

@copying
This file documents the Ido package for GNU Emacs.

Copyright @copyright{} 2013 Free Software Foundation, Inc.

@quotation
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with no
Invariant Sections, with the Front-Cover texts being ``A GNU Manual'',
and with the Back-Cover Texts as in (a) below.  A copy of the license
is included in the section entitled ``GNU Free Documentation License''.

(a) The FSF's Back-Cover Text is: ``You have the freedom to copy and
modify this GNU manual.''
@end quotation
@end copying

@dircategory Emacs misc features
@direntry
* Ido: (ido).                   Interactively do things with buffers and files.
@end direntry

@finalout

@titlepage
@sp 6
@center @titlefont{Interactive Do}
@sp 4
@center For GNU Emacs
@sp 1
@center as distributed with Emacs @value{EMACSVER}
@sp 5
@center Kim F. Storm
@center storm@@cua.dk
@page
@vskip 0pt plus 1filll
@insertcopying
@end titlepage

@contents

@ifnottex
@node Top
@top Interactive Do

@insertcopying
@end ifnottex

@menu
* Overview::                    Basics, activation.
* Matching::                    Interactivity, matching, scrolling.
* Highlighting::                Highlighting of matching items.
* Hidden Buffers and Files::    Hidden buffers, files, and directories.
* Customization::               Change the Ido functionality.
* Misc::                        Various other features.

Appendices
* GNU Free Documentation License::  The license for this documentation.

Indexes
* Variable Index::              An entry for each documented variable.

@detailmenu
 --- The Detailed Node Listing ---

Overview

* Activation::                  How to use this package.
* Working Directories::         Where files have most recently been opened.

Matching

* Interactive Substring Matching::  Interactivity, matching, scrolling.
* Prefix Matching::             Standard completion.
* Flexible Matching::           More flexible matching.
* Regexp Matching::             Matching using regular expression.

Customization

* Changing List Order::         Changing the list of files.
* Find File At Point::          Make Ido guess the context.
* Ignoring::                    Ignorance is bliss.
* Misc Customization::          Miscellaneous customization for Ido.

Miscellaneous

* All Matching::                Seeing all the matching buffers or files.
* Replacement::                 Replacement for @code{read-buffer} and @code{read-file-name}.
* Other Packages::              Don't want to depend on @code{ido-everywhere}?

@end detailmenu
@end menu

@node Overview
@chapter Overview
@cindex overview

@noindent
This document describes a set of features that can interactively do
things with buffers and files.  All the features are described here
in detail.

The @dfn{Ido} package can let you switch between buffers and visit
files and directories with a minimum of keystrokes.  It is a superset
of Iswitchb, the interactive buffer switching package by Stephen
Eglen.

@cindex author of Ido
@cindex Iswitchb
This package was originally written by Kim F. Storm, based on the
 @file{iswitchb.el} package by Stephen Eglen.

@menu
* Activation::                  How to use this package.
* Working Directories::         Where files have most recently been opened.
@end menu

@node Activation
@section Activation
@cindex activation
@cindex installation

@noindent
This package is distributed with Emacs, so there is no need to install
any additional files in order to start using it.  To activate, use
@kbd{M-x ido-mode}.

@noindent
You may wish to add the following expressions to your initialization
file (@pxref{Init File,,The Emacs Initialization File, emacs, GNU
Emacs Manual}), if you make frequent use of features from this
package.

@example
(require 'ido)
(ido-mode t)
@end example

@node Working Directories
@section Working Directories
@cindex working directories

@vindex ido-work-directory-list
@noindent
@dfn{Working directories} are directories where files have most
recently been opened.  The current directory is inserted at the front
of this @code{ido-work-directory-list} whenever a file is opened with
@code{ido-find-file} and other file-related functions.

@c @cindex merge
@c or maybe a new node for ``merge''

@c @deffn Command ido-merge-work-directories

@c @deffn Command ido-prev-work-directory

@c @deffn Command ido-next-work-directory

@c @deffn Command ido-forget-work-directory

@c @defvar ido-use-merged-list
@c @defvar ido-try-merged-list
@c @defvar ido-pre-merge-state

@defopt ido-max-work-directory-list
This user option specifies maximum number of working directories to
record.
@end defopt

@c see (info "(elisp) File Name Completion")
@defopt ido-max-dir-file-cache
This user option specifies maximum number of working directories to be
cached.  This is the size of the cache of
@code{file-name-all-completions} results.  Each cache entry is time
stamped with the modification time of the directory.  Some systems,
like MS-Windows, have unreliable directory modification times, so you
may choose to disable caching on such systems, or explicitly refresh
the cache contents using the command @code{ido-reread-directory}
(usually @kbd{C-l}) in the minibuffer.
@end defopt

@node Matching
@chapter Matching
@cindex matching

@noindent
This section describes features of this package that have to
do with various kinds of @emph{matching}: among buffers, files, and directories.

@menu
* Interactive Substring Matching::  Interactivity, matching, scrolling.
* Prefix Matching::             Standard completion.
* Flexible Matching::           More flexible matching.
* Regexp Matching::             Matching using regular expression.
@end menu

@node Interactive Substring Matching
@section Interactive Substring Matching
@cindex interactive substring matching
@cindex substring, interactive matching
@cindex matching, using substring

@noindent
As you type in a substring, the list of buffers or files currently
matching the substring are displayed as you type.  The list is
ordered so that the most recent buffers or files visited come at
the start of the list.

The buffer or file at the start of the list will be the one visited
when you press @key{RET}.  By typing more of the substring, the list
is narrowed down so that gradually the buffer or file you want will be
at the top of the list.  Alternatively, you can use @kbd{C-s} and
@kbd{C-r} (or the right and left arrow keys) to rotate buffer or file
names in the list until the one you want is at the top of the list.

Completion is also available so that you can see what is common to
all of the matching buffers or files as you type.

For example, if there are two buffers called @file{123456} and
@file{123}, with @file{123456} the most recent, when using
@code{ido-switch-buffer}, you first of all get presented with the list
of all the buffers

@example
Buffer: @{123456 | 123@}
@end example

If you then press @kbd{2}:

@example
Buffer: 2[3]@{123456 | 123@}
@end example

The list in @{...@} are the matching buffers, most recent first
(buffers visible in the current frame are put at the end of the list
by default).  At any time you can select the item at the head of the
list by pressing @key{RET}.  You can also put the first element at the
end of the list by pressing @kbd{C-s} or @kbd{<right>}, or bring the
last element to the head of the list by pressing @kbd{C-r} or
@kbd{<left>}.

The item in [...] indicates what can be added to your input by
pressing @key{TAB} (@code{ido-complete}).  In this case, you will get
"3" added to your input.

So, press @key{TAB}:

@example
Buffer: 23@{123456 | 123@}
@end example

At this point, you still have two matching buffers.  If you want the
first buffer in the list, you can simply press @key{RET}.  If you want
the second in the list, you can press @kbd{C-s} to move it to the top
of the list and then press @key{RET} to select it.

However, if you type @kbd{4}, you'll only have one match left:

@example
Buffer: 234[123456]
@end example

Since there is only one matching buffer left, it is given in [] and it
is shown in the @code{ido-only-match} face (ForestGreen).  You can now
press @key{TAB} or @key{RET} to go to that buffer.

If you want to create a new buffer named @file{234}, you can press
@kbd{C-j} (@code{ido-select-text}) instead of @key{TAB} or @key{RET}.

If instead, you type @kbd{a}:

@example
Buffer: 234a [No match]
@end example

There are no matching buffers.  If you press @key{RET} or @key{TAB},
you can be prompted to create a new buffer called @file{234a}.

Of course, where this function comes in really useful is when you can
specify the buffer using only a few keystrokes.  In the above example,
the quickest way to get to the @file{123456} file would be just to
type @kbd{4} and then @key{RET} (assuming there isn't any newer buffer
with @kbd{4} in its name).

Likewise, if you use @kbd{C-x C-f} (@code{ido-find-file}), the list of
files and directories in the current directory is provided in the same
fashion as the buffers above.  The files and directories are normally
sorted in alphabetical order, but the most recently visited directory
is placed first to speed up navigating to directories that you have
visited recently.

In addition to scrolling through the list using @kbd{<right>} and
@kbd{<left>}, you can use @kbd{<up>} and @kbd{<down>} to quickly
scroll the list to the next or previous subdirectory.

To go down into a subdirectory, and continue the file selection on
the files in that directory, simply move the directory to the head
of the list and hit @key{RET}.

To go up to the parent directory, delete any partial file name already
specified (e.g. using @key{DEL}) and hit @key{DEL}.

@c @deffn Command ido-delete-backward-updir

@cindex root directory
@cindex home directory
To go to the root directory (on the current drive), enter two slashes.
On MS-DOS or Windows, to select the root of another drive, enter
@samp{X:/} where @samp{X} is the drive letter.  To go to the home
directory, enter @samp{~/}.  To enter Dired for this directory, use
@kbd{C-d}.

@c TODO: a new node for ftp hosts
@cindex ftp hosts
You can also visit files on other hosts using the ange-ftp
notations @samp{/host:} and @samp{/user@@host:}.
@c @defopt ido-record-ftp-work-directories
@c @defopt ido-merge-ftp-work-directories
@c @defopt ido-cache-ftp-work-directory-time
@c @defopt ido-slow-ftp-hosts
@c @defopt ido-slow-ftp-host-regexps

You can type @kbd{M-p} and @kbd{M-n} to change to previous/next
directories from the history, @kbd{M-s} to search for a file matching
your input, and @kbd{M-k} to remove the current directory from the history.

If for some reason you cannot specify the proper file using
@code{ido-find-file}, you can press @kbd{C-f} to enter the normal
@code{find-file}.  You can also press @kbd{C-b} to drop into
@code{ido-switch-buffer}.

@c @kindex C-x b
@c @deffn Command ido-switch-buffer
@c This command switch to another buffer interactively.
@c @end deffn

@c @kindex C-x C-f
@c @deffn Command ido-find-file
@c Edit file with name obtained via minibuffer.
@c @end deffn

@c @kindex C-x d
@c @findex ido-dired
@c @deffn Command ido-dired
@c Call Dired the Ido way.
@c @end deffn

@node Prefix Matching
@section Prefix Matching
@cindex prefix matching
@cindex matching, using prefix
@cindex standard way of completion

@noindent
The standard way of completion with *nix shells and Emacs is to insert
a @dfn{prefix} and then hitting @key{TAB} (or another completion key).
Cause of this behavior has become second nature to a lot of Emacs
users Ido offers in addition to the default substring matching method
(look above) also the prefix matching method.  The kind of matching is
the only difference to the description of the substring matching
above.

@cindex toggle prefix matching
You can toggle prefix matching with @kbd{C-p}
(@code{ido-toggle-prefix}).

For example, if you have two buffers @file{123456} and @file{123} then
hitting @kbd{2} does not match because @kbd{2} is not a prefix in any
of the buffer names.

@node Flexible Matching
@section Flexible Matching
@cindex flexible matching

@defopt ido-enable-flex-matching
If non-@code{nil}, Ido will do flexible string matching.  Flexible
matching means that if the entered string does not match any item, any
item containing the entered characters in the given sequence will
match.
@end defopt

@noindent
If @code{ido-enable-flex-matching} is non-@code{nil}, Ido will do a
more flexible matching (unless regexp matching is active) to find
possible matches among the available buffer or file names if no
matches are found using the normal prefix or substring matching.

The flexible matching implies that any item which simply contains all
of the entered characters in the specified sequence will match.

For example, if you have four files @file{alpha}, @file{beta},
@file{gamma}, and @file{delta}, entering @samp{aa} will match
@file{alpha} and @file{gamma}, while @samp{ea} matches @file{beta} and
@file{delta}.  If prefix matching is also active, @samp{aa} only
matches @file{alpha}, while @samp{ea} does not match any files.

@node Regexp Matching
@section Regular Expression Matching
@cindex regexp matching
@cindex matching, using regular expression

@noindent
There is limited provision for regexp matching within Ido, enabled
through @code{ido-enable-regexp} (toggle with @kbd{C-t}).  This allows
you to type @samp{[ch]$} for example and see all file names ending in
@samp{c} or @samp{h}.

@defopt ido-enable-regexp
If the value of this user option is non-@code{nil}, Ido will do regexp
matching.  The value of this user option can be toggled within
ido-mode using @code{ido-toggle-regexp}.
@end defopt

@strong{Please notice:} Ido-style completion is inhibited when you
enable regexp matching.

@node Highlighting
@chapter Highlighting
@cindex highlighting

@noindent
The highlighting of matching items is controlled via
@code{ido-use-faces}.  The faces used are @code{ido-first-match},
@code{ido-only-match} and @code{ido-subdir}.

Coloring of the matching item was suggested by Carsten Dominik.

@node Hidden Buffers and Files
@chapter Hidden Buffers and Files
@cindex hidden buffers and files

Normally, Ido does not include hidden buffers (whose name starts with
a space) and hidden files and directories (whose name starts with
@samp{.}) in the list of possible completions.  However, if the
substring you enter does not match any of the visible buffers or
files, Ido will automatically look for completions among the hidden
buffers or files.

You can toggle display of the hidden buffers and files with @kbd{C-a}
(@code{ido-toggle-ignore}).

@c @deffn Command ido-toggle-ignore

@node Customization
@chapter Customization
@cindex customization

@noindent
You can customize the @code{ido} group to change Ido functionality:

@example
M-x customize-group RET ido RET
@end example

@noindent
or customize a certain variable:

@example
M-x customize-variable RET ido-xxxxx
@end example

To modify the keybindings, use the @code{ido-setup-hook}.  For example:

@example
(add-hook 'ido-setup-hook 'ido-my-keys)

(defun ido-my-keys ()
 "Add my keybindings for Ido."
 (define-key ido-completion-map " " 'ido-next-match))
@end example

@c @defopt ido-setup-hook
@c a new node for Ido hooks?

@menu
* Changing List Order::         Changing the list of files.
* Find File At Point::          Make Ido guess the context.
* Ignoring::                    Ignorance is bliss.
* Misc Customization::          Miscellaneous customization for Ido.
@end menu

@node Changing List Order
@section Changing List Order
@cindex changing order of the list

@noindent
By default, the list of current files is most recent first,
oldest last, with the exception that the files visible in the
current frame are put at the end of the list.  A hook exists to
allow other functions to order the list.  For example, if you add:

@example
(add-hook 'ido-make-buffer-list-hook 'ido-summary-buffers-to-end)
@end example

@noindent
then all files matching "Summary" are moved to the end of the list.
(I find this handy for keeping the INBOX Summary and so on out of the
way.)  It also moves files matching @samp{output\*$} to the end of the
list (these are created by AUCTeX when compiling.)  Other functions
could be made available which alter the list of matching files (either
deleting or rearranging elements.)

@node Find File At Point
@section Find File At Point
@cindex find file at point
@cindex ffap

@noindent
Find File At Point, also known generally as ``ffap'', is an
intelligent system for opening files, and URLs.

The following expression will make Ido guess the context:

@example
(setq ido-use-filename-at-point 'guess)
@end example

@c @defopt ido-use-filename-at-point
@c If the value of this user option is non-@code{nil}, ...
@c @end defopt

You can disable URL ffap support by toggling
@code{ido-use-url-at-point}.

@defopt ido-use-url-at-point
If the value of this user option is non-@code{nil}, Ido will look for
a URL at point.  If found, call @code{find-file-at-point} to visit it.
@end defopt

@node Ignoring
@section Ignoring Buffers and Files
@cindex ignoring
@cindex regexp, ignore buffers and files

@noindent
Ido is capable of ignoring buffers, directories, files and extensions
using regular expression.

@defopt ido-ignore-buffers
This variable takes a list of regular expressions for buffers to
ignore in @code{ido-switch-buffer}.
@end defopt

@defopt ido-ignore-directories
This variable takes a list of regular expressions for (sub)directories
names to ignore in @code{ido-dired} and @code{ido-find-file}.
@end defopt

@defopt ido-ignore-files
This variable takes a list of regular expressions for files to ignore
in @code{ido-find-file}.
@end defopt

@defopt ido-ignore-unc-host-regexps
This variable takes a list of regular expressions matching UNC hosts
to ignore.  The letter case will be ignored if
@code{ido-downcase-unc-hosts} is non-@code{nil}.
@end defopt

@c FIXME: Where to add this variable?  This node or ``working directory''?
@c @defopt ido-work-directory-list-ignore-regexps

To make Ido use @code{completion-ignored-extensions} you need to
enable it:

@example
(setq ido-ignore-extensions t)
@end example

Now you can customize @code{completion-ignored-extensions} as well.
Go ahead and add all the useless object files, backup files, shared
library files and other computing flotsam you don’t want Ido to show.

@strong{Please notice:} Ido will still complete the ignored elements
if it would otherwise not show any other matches.  So if you type out
the name of an ignored file, Ido will still let you open it just fine.

@node Misc Customization
@section Miscellaneous Customization
@cindex miscellaneous customization for Ido

@c Variables described in this sections may be moved to new nodes in
@c the future.

@defopt ido-mode
This user option determines for which functional group (buffer and
files) Ido behavior should be enabled.
@end defopt

@defopt ido-case-fold
If the value of this user option is non-@code{nil}, searching of
buffer and file names should ignore case.
@end defopt

@defopt ido-show-dot-for-dired
If the value of this user option is non-@code{nil}, always put
@samp{.}  as the first item in file name lists.  This allows the
current directory to be opened immediately with Dired
@end defopt

@defopt ido-enable-dot-prefix
If the value of this user option is non-@code{nil}, Ido will match
leading dot as prefix.  I.e., hidden files and buffers will match only
if you type a dot as first char (even if @code{ido-enable-prefix} is
@code{nil}).
@end defopt

@defopt ido-confirm-unique-completion
If the value of this user option is non-@code{nil}, even a unique
completion must be confirmed.  This means that @code{ido-complete}
(@key{TAB}) must always be followed by @code{ido-exit-minibuffer}
(@key{RET}) even when there is only one unique completion.
@end defopt

@defopt ido-cannot-complete-command
When @code{ido-complete} can't complete any more, it will run the
command specified by this user option.  The most useful values are
@code{ido-completion-help}, which pops up a window with completion
alternatives, or @code{ido-next-match} or @code{ido-prev-match}, which
cycle the buffer list.
@end defopt

@defopt ido-max-file-prompt-width
This user option specifies the upper limit of the prompt string.  If
its value is an integer, it specifies the number of characters of the
string.  If its value is a floating point number, it specifies a
fraction of the frame width.
@end defopt

@defopt ido-max-window-height
If the value of this user option is non-@code{nil}, its value will
override the variable @code{max-mini-window-height}, which is the
maximum height for resizing mini-windows (the minibuffer and the echo
area).  If it's a floating point number, it specifies a fraction of
the mini-window frame's height.  If it's an integer, it specifies the
number of lines.
@end defopt

@defopt ido-record-commands
If the value of this user option is non-@code{nil}, Ido will record
commands in the variable @code{command-history}.  Note that non-Ido
equivalent is recorded.
@end defopt

@defopt ido-all-frames
This user option will be passed to @code{walk-windows} as its
@var{all-frames} argument when Ido is finding buffers.  @xref{Cyclic
Window Ordering, , Cyclic Ordering of Windows, elisp, GNU Emacs Lisp
Reference Manual}.
@end defopt

@defopt ido-minibuffer-setup-hook
This hook variable contains Ido-specific customization of minibuffer
setup.  It is run during minibuffer setup if Ido is active, and is
intended for use in customizing ido for interoperation with other
packages.
@end defopt

@c @defopt ido-enable-tramp-completion
@c cross-reference to tramp.texi

@c @cindex UNC host names, completion
@c @defopt ido-unc-hosts
@c @defopt ido-downcase-unc-hosts
@c @defopt ido-cache-unc-host-shares-time

@c @defopt ido-enable-last-directory-history
@c @defopt ido-max-work-file-list
@c @defopt ido-work-directory-match-only
@c @defopt ido-auto-merge-work-directories-length
@c @defopt ido-auto-merge-delay-time
@c @defopt ido-auto-merge-inhibit-characters-regexp
@c @defopt ido-merged-indicator
@c @defopt ido-max-directory-size
@c @defopt ido-rotate-file-list-default
@c @defopt ido-enter-matching-directory
@c @defopt ido-create-new-buffer
@c @defopt ido-separator
@c @defopt ido-decorations
@c @defopt ido-use-virtual-buffers
@c @defopt ido-use-faces
@c @defopt ido-make-file-list-hook
@c @defopt ido-make-dir-list-hook
@c @defopt ido-make-buffer-list-hook
@c @defopt ido-rewrite-file-prompt-functions
@c @defopt ido-completion-buffer
@c @defopt ido-completion-buffer-all-completions
@c @defopt ido-save-directory-list-file
@c @defopt ido-read-file-name-as-directory-commands
@c @defopt ido-read-file-name-non-ido
@c @defopt ido-before-fallback-functions
@c @defopt ido-buffer-disable-smart-matches

@node Misc
@chapter Miscellaneous
@cindex miscellaneous

@noindent
After @kbd{C-x b} (@code{ido-switch-buffer}), the buffer at the head
of the list can be killed by pressing @kbd{C-k}.  If the buffer needs
saving, you will be queried before the buffer is killed.

Likewise, after @kbd{C-x C-f}, you can delete (i.e., physically
remove) the file at the head of the list with @kbd{C-k}.  You will
always be asked for confirmation before deleting the file.

If you enter @kbd{C-x b} to switch to a buffer visiting a given file,
and you find that the file you are after is not in any buffer, you can
press @kbd{C-f} to immediately drop into @code{ido-find-file}.  And
you can switch back to buffer selection with @kbd{C-b}.

@c @deffn Command ido-magic-forward-char
@c @deffn Command ido-magic-backward-char

You can also use Ido in your Emacs Lisp programs:

@example
(setq my-pkgs (list "CEDET" "Gnus" "Rcirc" "Tramp" "Org" "all-of-them"))
(ido-completing-read "What's your favorite package? " my-pkgs)
@end example

@menu
* All Matching::                Seeing all the matching buffers or files.
* Replacement::                 Replacement for @code{read-buffer} and @code{read-file-name}.
* Other Packages::              Don't want to depend on @code{ido-everywhere}?
@end menu

@node All Matching
@section All Matching
@cindex all matching
@cindex seeing all the matching buffers or files

@noindent
If you have many matching files, they may not all fit onto one line of
the minibuffer.  Normally, the minibuffer window will grow to show you
more of the matching files (depending on the value of the variables
@code{resize-mini-windows} and @code{max-mini-window-height}).  If you
want Ido to behave differently from the default minibuffer resizing
behavior, set the variable @code{ido-max-window-height}.

Also, to improve the responsiveness of Ido, the maximum number of
matching items is limited to 12, but you can increase or removed this
limit via the @code{ido-max-prospects} user option.

@c @defopt ido-max-prospects

To see a full list of all matching buffers in a separate buffer, hit
@kbd{?} or press @key{TAB} when there are no further completions to
the substring.  Repeated @key{TAB} presses will scroll you through
this separate buffer.

@node Replacement
@section Replacement

@noindent
@code{ido-read-buffer} and @code{ido-read-file-name} have been written
to be drop in replacements for the normal buffer and file name reading
functions @code{read-buffer} and @code{read-file-name}.

To use ido for all buffer and file selections in Emacs, customize the
variable @code{ido-everywhere}.

@c @deffn Command ido-everywhere
@c @defopt ido-everywhere

@node Other Packages
@section Other Packages
@cindex other packages
@cindex used by other packages

@noindent
If you don't want to rely on the @code{ido-everywhere} functionality,
@code{ido-read-buffer}, @code{ido-read-file-name}, and
@code{ido-read-directory-name} can be used by other packages to read a
buffer name, a file name, or a directory name in the @emph{Ido} way.

@c @node Cheatsheet

@c * History and Acknowledgments::     How Ido came into being
@c @node History and Acknowledgments
@c @appendix History and Acknowledgments

@node GNU Free Documentation License
@appendix GNU Free Documentation License
@include doclicense.texi

@c @node Function Index
@c @unnumbered Function Index

@c @printindex fn

@node Variable Index
@unnumbered Variable Index

@printindex vr

@bye