Icicles - History Enhancements

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History Enhancements

This page is about accessing and reusing previous input that you have typed in the minibuffer.

What Input, What History?

First, what is meant by “input” and “input history”? In Emacs and in this doc, “minibuffer history” and “input history” generally refer to input that you have typed (or cycled or completed) in the minibuffer and then entered using ‘RET’ (or ‘S-RET’). Emacs provides different history lists for this, depending on the kind of input. The most general such list is the value of variable ‘minibuffer-history’.

But what about input that you type in the minibuffer (e.g. during completion) but that you do not enter with ‘RET’? That is not recorded in any standard history list, so you cannot recall it using ‘M-p’ and ‘M-n’.

The Icicles doc speaks ambiguously of “minibuffer input”. This always refers to something that you type in the minibuffer, but sometimes it means input that you enter with ‘RET’ and sometimes it does not. The context and the use of phrases such as “entered” and “entered with ‘RET’” should make clear what is meant. Input that you type during completion but you do not necessarily enter is sometimes referred to in the Icicles doc as “completion input”.

Icicles also records any input that you type during completion but you do not enter (‘RET’ or ‘mouse-2’), because you might need to retrieve it. This can be because you cycled among completion candidates (cycling replaces the input you type) or because Icicles has expanded your input to the common match among all matching candidates (see option `icicle-expand-input-to-common-match’).

You can retrieve the last such unentered input during completion using ‘C-l’ (‘icicle-retrieve-previous-input’) and ‘C-S-l’, that is, ‘C-L’, (‘icicle-retrieve-next-input’). Use these commands to cycle among your past completion inputs (backward and forward, respectively).

User option `icicle-completion-history-max-length’ limits the number of completion inputs to save.

If you customize user option `icicle-C-l-uses-completion-flag’ to non-‘nil’, then, instead of cycling, ‘C-l’ lets you use Icicles completion to retrieve a past completion input (‘C-L’ does the same thing). Using completion to retrieve a past input does not also choose that input as the candidate for the main completion; it just replaces your current minibuffer input with it. Because ‘C-l’ completion uses a recursive minibuffer, you can also use ‘C-g’ to cancel this completion and return to the main completion.

You can temporarily reverse the effect of ‘icicle-C-l-uses-completion-flag’ by using a prefix argument (‘C-u’) with ‘C-l’. Thus, ‘C-u C-l’ uses completion if ‘icicle-C-l-uses-completion-flag’ is ‘nil’ and cycles if it is non-‘nil’.

The other sections on this page describe Icicles enhancements for minibuffer histories. They are thus concerned only with inputs that you enter, not with completion inputs that are not entered.

Overview of Minibuffer History Enhancements

Icicles enhances minibuffer history during completion in these independent ways:

1. Commands invoked using a menu bar menu are included in the command history for ‘M-x’. This helps you quickly find again and reuse a (possibly deep) menu item. It lets you use completion to access such commands. And it helps you learn the commands that correspond to menu items that you use, thus providing a missing bridge between menu use and minibuffer use.

If you do not want to include menu-item commands in the command history, then set option `icicle-menu-items-to-history-flag’ to ‘nil’.

Note: Non-‘nil’ ‘icicle-menu-items-to-history-flag’ simply makes Emacs handle menu items that you choose the same way that it handles commands that you enter using ‘RET’. It does not add such menu items to your completion history, which you access using ‘C-l’ (see What Input, What History?).

2. Minibuffer multi-command ‘icicle-insert-history-element’ (‘M-o’ in the minibuffer) lets you use completion to insert any number of history elements in the minibuffer.

3. Candidates displayed in ‘*Completions*’ are highlighted using face ‘icicle-historical-candidate’ (blue foreground, by default), when they have been used previously, so you can more easily recognize them. This highlighting is controlled by option `icicle-highlight-historical-candidates-flag’. You can toggle this from the minibuffer at any time using ‘C-pause’.

4. Command ‘icicle-toggle-alternative-sorting’ (`C-M-,’ in the minibuffer) re-sorts completion candidates, placing previously used candidates first. This is a toggle: repeat it to return to the original order.

5. Command ‘icicle-keep-only-past-inputs’ (‘M-pause’ in the minibuffer) restricts the current set of completion candidates to those that you have used previously. In other words, it keeps only those candidates that are highlighted in blue. To use ‘M-pause’, you must first have used ‘TAB’ or ‘S-TAB’ to establish an explicit candidate set. If you use ‘C-u M-pause’, then the previously used candidates are ordered chronologically, most recent first. Without ‘C-u’, the normal sort order is used (‘icicle-sort-comparer’).

6. Command ‘icicle-history’ (‘M-h’ in the minibuffer) matches the current input against the minibuffer history directly. It can be used during completion.

7. Command ‘icicle-other-history’ (‘C-M-pause’ in the minibuffer) lets you use a different history for the minibuffer reading. You can choose the history using completion (even if the main minibuffer reading does not allow completion).

You can choose among any variables whose names end in ‘history’ or ‘ring’, which includes the Isearch histories ‘search-ring’ and ‘regexp-search-ring’.

8. Commands ‘icicle-clear-history’ and ‘icicle-clear-current-history’ (‘M-K’ in the minibuffer) provide a general way to clean up histories.

9. When you cycle among previously entered inputs using ‘M-p’ and ‘M-n’, you can use ‘M-k’ (command ‘icicle-erase-minibuffer-or-history-element’) to delete the current occurrence from the history list. This is a quick and handy way to clean up list entries that you are no longer interested in. Only the occurrence that you have cycled to is deleted; if there are identical entries elsewhere in the history, they remain.

Some of these enhancements are described below in more detail. Each of 1-7 lets you see the complete list of previous inputs that match your current input.

In vanilla Emacs, the history lists are never shown as such; you can access previous inputs only one at a time, in order (with ‘M-p’). In vanilla Emacs, you can use a regexp to search the history list (via ‘M-r’ and ‘M-s’), but the regexp matching is not dynamic, and the first match found is the only one you get. In Icicle mode, ‘M-r’ and ‘M-s’ are not available for matching a history item — use ‘M-o’ instead (see next).

Displaying previous inputs that match the current input sounds like a minor advantage, but it is actually quite helpful in practice. Among other things, it means that you can work with long history lists in a practical way.

Using Completion to Insert Previous Inputs: `M-o'

Unlike the other minibuffer history enhancements, described below, which are available only during minibuffer completion, you can use ‘M-o’ (‘icicle-insert-history-element’) anytime you are asked for minibuffer input. It is thus a form of on-demand completion (see Icicles - Completion On Demand. It provides a recursive minibuffer in which you can match previous inputs using completion.

This is a multi-command: you use ‘C-RET’ etc. to choose matching previous inputs as candidates using a recursive minibuffer. Yes, you can even use `C-!’ to choose all matching candidates, inserting them in the current sort order.

When you are finished choosing candidates, use ‘C-g’ (or ‘RET’) to exit to the previous minibuffer level. All of the previous inputs you chose are inserted into the upper-level minibuffer, in order.

This is better than cycling with ‘M-n’ or ‘M-p’, or searching with ‘M-s’ or ‘M-r’ in vanilla Emacs: You can use Icicles completion and cycling to quickly access a previous input, no matter how long ago you entered it.

When completion is available for reading input, if you use ‘M-o’ to choose previously entered inputs, this just inserts that text into the minibuffer. What is in the minibuffer after you use ‘M-o’ is not used automatically and immediately for the main completion – you can edit it before entering it using ‘RET’.

Here’s an example: Reuse a previous Isearch search string as the content-matching part of your multi-completion input for ‘C-x C-f’ (‘icicle-file’) or ‘C-x b’ (‘icicle-buffer’):

  1. ‘C-x C-f C-M-j C-M-pause’
  2. Choose ‘regexp-search-ring’ (or ‘search-ring’) as the history to use.
  3. ‘M-o S-TAB’
  4. Choose a previous search string to insert, then complete to find a file whose content matches it.

Reminder:

Multi-Input Insertion with a Prefix Arg

This section describes the use of a prefix argument with ‘M-o’ (‘icicle-insert-history-element’). It also applies to ‘M-r’ (‘icicle-roundup’).

Because ‘M-o’ lets you insert more than one previous input, there are different ways to separate these insertions, depending on the prefix argument.

These possibilities provide for different uses of such insertion:

A prefix argument to ‘M-o’ applies to each of the candidates you choose, by default. If you use a prefix argument then you will typically want to exit using ‘C-g’ (not ‘RET’), so the prefix argument applies also to the last candidate chosen.

You can override the prefix argument for ‘M-o’ or lack thereof, by using a prefix argument for an individual candidate action (e.g. ‘C-u C-RET’).

Putting Previous Candidates First: `C-M-,'

At any time, two of the Icicles sort orders are immediately available. These are the values of user options `icicle-sort-comparer’ and `icicle-alternative-sort-comparer’. By default, the former usually sorts alphabetically, and the latter puts all previously used inputs first, before the candidates you have not yet used. Each of these groups, used and unused candidates, is then sorted alphabetically, separately. So, with the default alternative sort, you can see all matching candidates (used and unused), but you privilege those used previously – they are the first listed in ‘*Completions*’ and the first available for cycling.

If you prefer, by customizing these user options, you can use ‘icicle-historical-alphabetic-p’ as the main sort function (option ‘icicle-sort-comparer’) and some other sort function (e.g. ‘icicle-case-string-less-p’) as the alternative sort function.

You can toggle at any time between normal sorting and alternative sorting, using command ‘icicle-toggle-alternative-sorting’. During completion, this is bound to `C-M-,’. Together with toggling between normal sorting and not sorting at all, which is a sort-order choice available through`C-,’, this gives you quite a lot of flexibility.

Matching Only Historical Candidates: `M-h' and `M-pause'

Both ‘M-h’ (‘icicle-history’) and ‘M-pause’ (‘icicle-keep-only-past-inputs’) can be used toward the same end. They both work for all input types. They both use the appropriate history list for the current command. They both provide completion and cycling for the minibuffer history. Use them as another way to search through a history list or complete to one of its elements.

For example, If you use ‘C-x C-f’ to find a file, and then use ‘M-h’ or ‘M-pause’, the completion candidates will be the names of files that you have previously accessed (file names you have input in the minibuffer), and which match the current minibuffer input.

‘M-h’ lets you complete your input against the minibuffer input history. ‘M-pause’ lets you restrict the current explicit set of completion candidates to those that are also in the minibuffer history.

They provide similar functionality in different ways. The difference is that ‘M-pause’ takes the current set of matching candidates into account. It is a completion-candidates set operation, similar to those described in Icicles - Candidate Sets.

This means, in particular, that with ‘M-pause’ you can first perform set operations on the set of candidates, and then use that result to restrict the history search. For example, you can first complement the candidate set using `C-~’, then use ‘M-pause’ to restrict those candidates to matches in the history list. In this way, you avoid including matches from the original match set when searching the history.

Example: You are in a directory with lots of files that have the prefix ‘foo’ and lots of C-language source files. You happen to be interested in another file, however. One way to get to that file is to use Dired’s ability to mark files by matching a regexp and then use Dired’s ability to omit the marked files from view. You can scan through those that remain, and pick the one you want. However, it turns out that even then there are many files to scan. You accessed the one you want now just the other day, but the file date is unfortunately not significant.

In Icicles, you use regexp matching and take the set complement of the hits, just like in Dired: `C-x C-f foo.*\.c$’ defines the candidate set as all files whose names start with ‘foo’ and have extension ‘c’. `C-~’ then defines the candidate set as all files whose names are not like that. Finally, you use ‘M-pause’ to restrict the file-name candidates to names that you have used before. You’ve accessed many, many files recently, so just cycling through the history with ‘M-p’ would be tedious. You could match a regexp against the file history, but how can you come up with a regexp that finds anti-matches?

A consequence of this difference between ‘M-h’ and ‘M-pause’ is that using ‘TAB’ or ‘S-TAB’ after ‘M-pause’ abandons use of the minibuffer history and starts a new set of completion candidates. It simply completes the current input in the context of the current command; ‘TAB’ and ‘S-TAB’ have nothing to do with the minibuffer history in this case. Using ‘TAB’ or ‘S-TAB’ after ‘M-h’, however, re-completes your input against the current history list.

Another consequence is that you can use ‘down’ or ‘C-down’ on the candidates displayed by ‘M-h’, but not on those displayed by ‘M-pause’. For example, to cycle through the doc for each variable that starts with ‘icicle-’ which you have previously input, you can use `C-h v icicle- M-h’, then repeatedly use ‘C-down’.

Also, file-name and directory-name completion works differently in these two commands. By default, the current directory is (as always) inserted into the minibuffer by commands such as ‘find-file’, so either ‘M-h’ or ‘M-pause’ after ‘C-x C-f’ will match previously input file names from the current directory. However, in the case of ‘M-h’, the entire minibuffer input is matched against the history list, which is a list of absolute file names. ‘M-pause’ works only with the current candidate set, which, if you have already used ‘TAB’ or ‘S-TAB’ in the current directory, is a set of relative file names in that directory.

This difference has a consequence for apropos (regexp) completion with ‘M-h’. It means that to match a file name using a substring you must, in the minibuffer, either not specify a directory (erase it) or explicitly use `.*’ before the file-name substring. For example, with ‘M-h’, ‘/foo/bar/lph’ will not apropos-match the previously input file name `/foo/bar/alphabet-soup.el’; you should use either `/foo/bar/.*lph’ or ‘lph’ (no directory).

In the case of ‘M-pause’, however, the input is matched against the history list as restricted by the existing completion list. And, since apropos file-name completion uses only the relative file name, without the directory name, as a regexp, the candidate list that is restricted has already matched the input regexp. The action of ‘M-pause’ is simply to filter the list of candidates, keeping those that are in the history list. This means that, with ‘M-pause’, the input ‘/foo/bar/lph’ will match against the previously input file name `/foo/bar/alphabet-soup.el’.

Note that neither ‘M-h’ nor ‘M-pause’ uses a recursive minibuffer; they each simply co-opt the current completion, changing it to completion against the history. This means that whatever completion mode (prefix or apropos) was in effect before you use ‘M-h’ or ‘M-pause’ remains in effect for the history completion as well.

If this all sounds confusing, just give it a try; it is much harder to describe than it is to experience.

Using Other Histories; Commands Any Which Way

This section describes how to complete your input against a history other than the default history provided for the current command. A special case of this, starting with Emacs 23, is completing a command, abbrev, or keyboard macro name against all such that were previously executed in any interactive way. This includes commands invoked using a menu.

Completing Against All Interactive Commands

When you execute a command using ‘M-x’, it is added to the history ‘extended-command-history’. Likewise, when you execute a command or abbrev using ‘icicle-command-abbrev-command’. And when you execute a keyboard macro using ‘C-x M-e’ (‘icicle-execute-named-keyboard-macro’), it is added to history ‘icicle-kmacro-history’.

However, when you execute a command, abbrev, or keyboard macro in other ways than these, it is not added to such a history. For example, if you choose a menu item, the associated command is not added to any of these histories. Thus, although ‘M-o’ lets you complete against previously used commands, this does not include commands that were called via a menu item.

To remedy this, starting with Emacs 23 Icicles can optionally add all commands that are called using ‘call-interactively’ to the larger command history ‘icicle-interactive-history’. This includes commands on menus. To enable this feature, you must customize option `icicle-populate-interactive-history-flag’, to make it non-‘nil’. Thereafter, when you enter Icicle mode, all interactive use of commands records them on this special history.

Be aware that use of this feature can slow Emacs down, and the history list can become quite large.

During completion, you can then use ‘C-M-pause’ (‘icicle-other-history’) to complete against this extended set of previously used commands. For example, if you use menu item Open File, then the corresponding command, ‘menu-find-file-existing’, becomes available as a completion candidate. (Recall too that the command associated with a given menu item is shown in the ‘*Completions*’ mode line whenever you cycle to it.) This is a special case of using ‘C-M-pause’, of which see more below.

Using an Alternative History

Anytime you enter input in the minibuffer, regardless of whether completion is available, ‘C-M-pause’ prompts you for an alternative history to use – any history you like. You can choose the history using completion.

That is, you can change which history to use, on the fly, as many times as you like. You can use this before using ‘M-o’, for instance, to complete against different histories for different parts of your overall minibuffer input. If you are inputting a complex shell command with arguments, for example, you can use different histories to compose different parts of the overall command.

(If you are completing a command, abbrev, or keyboard macro, then for ‘C-M-pause’ to prompt for an alternative history you must use a prefix argument. Otherwise, you get the special ‘C-M-pause’ behavior described above – see Completing Against All Interactive Commands, above.

Cleaning Up History Lists

Besides the use of ‘M-k’ during history cycling (‘M-p’, ‘M-n’) to remove individual input occurrences from the current history list, you can use commands ‘icicle-clear-history’ and ‘icicle-clear-current-history’ to clean minibuffer histories entirely of selected entries. Command ‘icicle-clear-current-history’ is bound to ‘M-K’ in the minibuffer. It is ‘icicle-clear-history’ specialized to work on just the current history list.

These commands prompt you for a history entry to delete from a history list. These are multi-commands, so you can delete multiple entries. For each entry you choose, all of its occurrences are deleted from the history.

Command ‘icicle-clear-history’ first prompts you for a history list to act on. This too is multi-command input, so you can use ‘icicle-clear-history’ to remove entries from multiple histories.

If you use a prefix argument with these commands, then the histories are emptied entirely (upon confirmation). Thus, for instance, you can use ‘C-u M-i’ at any time during minibuffer input to completely empty the current history list.

See Also: Icicles - More About Multi-Commands for information about using ‘S-delete’ to delete objects associated with completion candidates.


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