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Ediff has a rather self-explanatory interface, and in most cases you won't need to change anything. However, should the need arise, there are extensive facilities for changing the default behavior.
Most of the customization can be done by setting various variables in the `.emacs' file. Some customization (mostly window-related customization and faces) can be done by putting appropriate lines in `.Xdefaults', `.xrdb', or whatever X resource file is in use.
With respect to the latter, please note that the X resource for Ediff customization is `Ediff', not `emacs'. See section 7.3 Window and Frame Configuration, See section 7.5 Highlighting Difference Regions, for further details. Please also refer to Emacs manual for the information on how to set Emacs X resources.
7.1 Hooks | Customization via the hooks. | |
7.2 Quick Help Customization | How to customize Ediff's quick help feature. | |
7.3 Window and Frame Configuration | Controlling the way Ediff displays things. | |
7.4 Selective Browsing | Advanced browsing through difference regions. | |
7.5 Highlighting Difference Regions | Controlling highlighting. | |
7.6 Narrowing | Comparing regions, windows, etc. | |
7.7 Refinement of Difference Regions | How to control the refinement process. | |
7.8 Patch and Diff Programs | Changing the utilities that compute differences and apply patches. | |
7.9 Merging and diff3 | How to customize Ediff in its Merge Mode. | |
7.10 Support for Version Control | Changing the version control package. You are not likely to do that. | |
7.11 Customizing the Mode Line | Changing the look of the mode line in Ediff. | |
7.12 Miscellaneous | Other customization. | |
7.13 Notes on Heavy-duty Customization | Customization for the gurus. |
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The bulk of customization can be done via the following hooks:
ediff-load-hook
ediff-before-setup-hook
ediff-keymap-setup-hook
ediff-mode-map
. These hooks are
run right after the default bindings are set but before
ediff-load-hook
. The regular user needs not be concerned with this
hook--it is provided for implementors of other Emacs packages built on top
of Ediff.
ediff-before-setup-windows-hook
ediff-after-setup-windows-hook
ediff-suspend-hook
ediff-quit-hook
By default, ediff-quit-hook
holds one hook function,
ediff-cleanup-mess
, which cleans after Ediff, as appropriate in
most cases. You probably won't want to change it, but you might
want to add other hook functions.
Keep in mind that hooks executing before ediff-cleanup-mess
start
in ediff-control-buffer;
they should also leave
ediff-control-buffer
as the current buffer when they finish.
Hooks that are executed after ediff-cleanup-mess
should expect
the current buffer be either buffer A or buffer B.
ediff-cleanup-mess
doesn't kill the buffers being compared or
merged (see ediff-cleanup-hook
, below).
ediff-cleanup-hook
ediff-quit-hook
. This is a good
place to do various cleanups, such as deleting the variant buffers.
Ediff provides a function, ediff-janitor
, as one such possible
hook, which you can add to ediff-cleanup-hook
with
add-hooks
.
This function kills buffers A, B, and, possibly, C, if these buffers aren't modified. In merge jobs, buffer C is never deleted. However, the side effect of using this function is that you may not be able to compare the same buffer in two separate Ediff sessions: quitting one of them will delete this buffer in another session as well.
ediff-quit-merge-hook
ediff-maybe-save-and-delete-merge
, which is a function that attempts
to save the merge buffer according to the value of
ediff-autostore-merges
, as described later.
ediff-before-setup-control-frame-hook
ediff-after-setup-control-frame-hook
ediff-control-buffer
), which requires
special care in writing these hooks. Take a look at
ediff-default-suspend-hook
and ediff-default-quit-hook
to
see what's involved.
ediff-startup-hook
ediff-select-hook
ediff-unselect-hook
ediff-prepare-buffer-hook
ediff-display-help-hook
ediff-mode-hook
ediff-registry-setup-hook
ediff-before-session-group-setup-hook
ediff-after-session-group-setup-hook
ediff-quit-session-group-hook
ediff-meta-buffer-keymap-setup-hook
ediff-meta-buffer-map
-- the
map that controls key bindings in the meta buffer. Since
ediff-meta-buffer-map
is a local variable, you can set different
bindings for different kinds of meta buffers.
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Ediff provides quick help using its control panel window. Since this window takes a fair share of the screen real estate, you can toggle it off by typing ?. The control window will then shrink to just one line and a mode line, displaying a short help message.
The variable ediff-use-long-help-message
tells Ediff whether
you use the short message or the long one. By default, it
is set to nil
, meaning that the short message is used.
Set this to t
, if you want Ediff to use the long
message by default. This property can always be changed interactively, by
typing ? into Ediff Control Buffer.
If you want to change the appearance of the help message on a per-buffer
basis, you must use ediff-startup-hook
to change the value of
the variable ediff-help-message
, which is local to
ediff-control-buffer
.
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On a non-windowing display, Ediff sets things up in one frame, splitting it between a small control window and the windows for buffers A, B, and C. The split between these windows can be horizontal or vertical, which can be changed interactively by typing | while the cursor is in the control window.
On a window display, Ediff sets up a dedicated frame for Ediff Control
Panel and then it chooses windows as follows: If one of the buffers
is invisible, it is displayed in the currently selected frame. If
a buffer is visible, it is displayed in the frame where it is visible.
If, according to the above criteria, the two buffers fall into the same
frame, then so be it--the frame will be shared by the two. The same
algorithm works when you type C-l (ediff-recenter
), p
(ediff-previous-difference
), n
(ediff-next-difference
), etc.
The above behavior also depends on whether the current frame is splittable, dedicated, etc. Unfortunately, the margin of this book is too narrow to present the details of this remarkable algorithm.
The upshot of all this is that you can compare buffers in one frame or in different frames. The former is done by default, while the latter can be achieved by arranging buffers A, B (and C, if applicable) to be seen in different frames. Ediff respects these arrangements, automatically adapting itself to the multi-frame mode.
Ediff uses the following variables to set up its control panel (a.k.a. control buffer, a.k.a. quick help window):
ediff-control-frame-parameters
ediff-control-frame-parameters
directly. For instance, you can
specify in `~/.Xdefaults' the color of the control frame
using the resource `Ediff*background'.
In general, any X resource pertaining the control frame can be reached
via the prefix Ediff*
.
ediff-control-frame-position-function
ediff-control-frame-position-function
to an
appropriate function.
The default value of this variable is
ediff-make-frame-position
. This function places the control frame in
the vicinity of the North-East corner of the frame displaying buffer A.
The following variables can be used to adjust the location produced by
ediff-make-frame-position
and for related customization.
ediff-narrow-control-frame-leftward-shift
ediff-wide-control-frame-rightward-shift
ediff-control-frame-upward-shift
ediff-prefer-iconified-control-frame
t
, the control frame becomes iconified
automatically when you toggle the quick help message off. This saves
valuable real estate on the screen. Toggling help back will deiconify
the control frame.
To start Ediff with an iconified Control Panel, you should set this
variable to t
and ediff-prefer-long-help-message
to
nil
(see section 7.2 Quick Help Customization). This behavior is useful
only if icons are allowed to accept keyboard input (which depends on the
window manager and other factors).
To make more creative changes in the way Ediff sets up windows, you can
rewrite the function ediff-setup-windows
. However, we believe
that detaching Ediff Control Panel from the rest and making it into a
separate frame offers an important opportunity by allowing you to
iconify that frame. The icon will usually accept all of the Ediff
commands, but will free up valuable real estate on your screen (this may
depend on your window manager, though).
The following variable controls how windows are set up:
ediff-window-setup-function
ediff-setup-windows-multiframe
function, which is the default on
windowing displays. The plain setup, one where all windows are always
in one frame, is done by ediff-setup-windows-plain
, which is the
default on a non-windowing display (or in an xterm window). In fact,
under Emacs, you can switch freely between these two setups by executing
the command ediff-toggle-multiframe
using the Minibuffer of the
Menubar.
If you don't like any of these setups, write your own function. See the
documentation for ediff-window-setup-function
for the basic
guidelines. However, writing window setups is not easy, so you should
first take a close look at ediff-setup-windows-plain
and
ediff-setup-windows-multiframe
.
You can run multiple Ediff sessions at once, by invoking Ediff several times without exiting previous Ediff sessions. Different sessions may even operate on the same pair of files.
Each session has its own Ediff Control Panel and all the regarding a particular session is local to the associated control panel buffer. You can switch between sessions by suspending one session and then switching to another control panel. (Different control panel buffers are distinguished by a numerical suffix, e.g., `Ediff Control Panel<3>'.)
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Sometimes it is convenient to be able to step through only some difference regions, those that match certain regular expressions, and to ignore all others. On other occasions, you may want to ignore difference regions that match some regular expressions, and to look only at the rest.
The commands #f and #h let you do precisely this.
Typing #f lets you specify regular expressions that match difference regions you want to focus on. We shall call these regular expressions regexp-A, regexp-B and regexp-C. Ediff will then start stepping through only those difference regions where the region in buffer A matches regexp-A and/or the region in buffer B matches regexp-B, etc. Whether `and' or `or' will be used depends on how you respond to a question.
When scanning difference regions for the aforesaid regular expressions, Ediff narrows the buffers to those regions. This means that you can use the expressions \` and \' to tie search to the beginning or end of the difference regions.
On the other hand, typing #h lets you specify (hide) uninteresting
regions. That is, if a difference region in buffer A matches
regexp-A, the corresponding region in buffer B matches regexp-B
and (if applicable) buffer C's region matches regexp-C, then the
region will be ignored by the commands n/SPC
(ediff-next-difference
) and p/DEL
(ediff-previous-difference
) commands.
Typing #f and #h toggles selective browsing on and off.
Note that selective browsing affects only ediff-next-difference
and ediff-previous-difference
, i.e., the commands
n/SPC and p/DEL. #f and #h do not
change the position of the point in the buffers. And you can still jump
directly (using j) to any numbered
difference.
Users can supply their own functions to specify how Ediff should do
selective browsing. To change the default Ediff function, add a function to
ediff-load-hook
which will do the following assignments:
(setq ediff-hide-regexp-matches-function 'your-hide-function) (setq ediff-focus-on-regexp-matches-function 'your-focus-function) |
Useful hint: To specify a regexp that matches everything, don't simply type RET in response to a prompt. Typing RET tells Ediff to accept the default value, which may not be what you want. Instead, you should enter something like ^ or $. These match every line.
You can use the status command, i, to find out whether selective browsing is currently in effect.
The regular expressions you specified are kept in the local variables
ediff-regexp-focus-A
, ediff-regexp-focus-B
,
ediff-regexp-focus-C
, ediff-regexp-hide-A
,
ediff-regexp-hide-B
, ediff-regexp-hide-C
. Their default value
is the empty string (i.e., nothing is hidden or focused on). To change the
default, set these variables in `.emacs' using setq-default
.
In addition to the ability to ignore regions that match regular expressions, Ediff can be ordered to start skipping over certain "uninteresting" difference regions. This is controlled by the following variable:
ediff-ignore-similar-regions
t
, causes Ediff to skip over "uninteresting" difference regions,
which are the regions where the variants differ only in the amount of the
white space and newlines. This feature can be toggled on/off interactively,
via the command ##.
Please note: in order for this feature to work, auto-refining of difference regions must be on, since otherwise Ediff won't know if there are fine differences between regions. On devices where Emacs can display faces, auto-refining is a default, but it is not turned on by default on text-only terminals. In that case, you must explicitly turn auto-refining on (such as, by typing @).
Reassurance: If many such uninteresting regions appear in a row, Ediff may take a long time to skip over them because it has to compute fine differences of all intermediate regions. This delay does not indicate any problem.
Finally, Ediff can be told to ignore the case of the letters. This behavior
can be toggled with #c and it is controlled with three variables:
ediff-ignore-case-option
, ediff-ignore-case-option3
, and
ediff-ignore-case
.
The variable ediff-ignore-case-option
specifies the option to pass
to the diff program for comparing two files or buffers. For GNU
diff
, this option is "-i"
. The variable
ediff-ignore-case-option3
specifies the option to pass to the
diff3
program in order to make it case-insensitive. GNU diff3
does not have such an option, so when merging or comparing three files with
this program, ignoring the letter case is not supported.
The variable ediff-ignore-case
controls whether Ediff starts out by
ignoring letter case or not. It can be set in `.emacs' using
setq-default
.
When case sensitivity is toggled, all difference regions are recomputed.
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The following variables control the way Ediff highlights difference regions:
ediff-before-flag-bol
ediff-after-flag-eol
ediff-before-flag-mol
ediff-after-flag-mol
ediff-current-diff-face-A
ediff-current-diff-face-B
ediff-current-diff-face-C
ediff-fine-diff-face-A
ediff-fine-diff-face-B
ediff-fine-diff-face-C
ediff-even-diff-face-A
ediff-even-diff-face-B
ediff-even-diff-face-C
ediff-odd-diff-face-A
ediff-odd-diff-face-B
ediff-odd-diff-face-C
ediff-force-faces
t
to make sure that
Ediff uses faces to highlight differences.
ediff-highlight-all-diffs
ediff-highlight-all-diffs
to nil
. Type h to
restore highlighting for all differences.
Ediff lets you switch between the two modes of highlighting. That is, you can switch interactively from highlighting using faces to highlighting using string flags, and back. Of course, switching has effect only under a windowing system. On a text-only terminal or in an xterm window, the only available option is highlighting with strings.
If you want to change the default settings for ediff-force-faces
and
ediff-highlight-all-diffs
, you must do it before Ediff is
loaded.
You can also change the defaults for the faces used to highlight the difference regions. There are two ways to do this. The simplest and the preferred way is to use the customization widget accessible from the menubar. Ediff's customization group is located under "Tools", which in turn is under "Programming". The faces that are used to highlight difference regions are located in the "Highlighting" subgroup of the Ediff customization group.
The second, much more arcane, method to change default faces is to include some Lisp code in `~/.emacs'. For instance,
(setq ediff-current-diff-face-A (copy-face 'bold-italic 'ediff-current-diff-face-A)) |
would use the pre-defined face bold-italic
to highlight the current
difference region in buffer A (this face is not a good choice, by the way).
If you are unhappy with just some of the aspects of the default
faces, you can modify them when Ediff is being loaded using
ediff-load-hook
. For instance:
(add-hook 'ediff-load-hook (lambda () (set-face-foreground ediff-current-diff-face-B "blue") (set-face-background ediff-current-diff-face-B "red") (make-face-italic ediff-current-diff-face-B))) |
Please note: to set Ediff's faces, use only copy-face
or set/make-face-...
as shown above. Emacs' low-level
face-manipulation functions should be avoided.
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If buffers being compared are narrowed at the time of invocation of
Ediff, ediff-buffers
will preserve the narrowing range. However,
if ediff-files
is invoked on the files visited by these buffers,
that would widen the buffers, since this command is defined to compare the
entire files.
Calling ediff-regions-linewise
or ediff-windows-linewise
, or
the corresponding `-wordwise' commands, narrows the variants to the
particular regions being compared. The original accessible ranges are
restored when you quit Ediff. During the command, you can toggle this
narrowing on and off with the % command.
These two variables control this narrowing behavior:
ediff-start-narrowed
t
, Ediff narrows the display to the appropriate range when it
is invoked with an `ediff-regions...' or
`ediff-windows...' command. If nil
, these commands do
not automatically narrow, but you can still toggle narrowing on and off
by typing %.
ediff-quit-widened
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Ediff has variables to control the way fine differences are highlighted. This feature gives you control over the process of refinement. Note that refinement ignores spaces, tabs, and newlines.
ediff-auto-refine
On a slow machine, automatic refinement may be painful. In that case, you can turn auto-refining on or off interactively by typing @. You can also turn off display of refining that has already been done.
When auto-refining is off, fine differences are shown only for regions for which these differences have been computed and saved before. If auto-refining and display of refining are both turned off, fine differences are not shown at all.
Typing * computes and displays fine differences for the current difference region, regardless of whether auto-refining is turned on.
ediff-auto-refine-limit
You can always refine the current region by typing *.
ediff-forward-word-function
Fine differences are computed by first splitting the current difference
region into words and then passing the result to
ediff-diff-program
. For the default forward word function (which is
ediff-forward-word
), a word is a string consisting of letters,
`-', or `_'; a string of punctuation symbols; a string of digits,
or a string consisting of symbols that are neither space, nor a letter.
This default behavior is controlled by four variables: ediff-word-1
,
..., ediff-word-4
. See the on-line documentation for these variables
and for the function ediff-forward-word
for an explanation of how to
modify these variables.
Sometimes, when a region has too many differences between the variants, highlighting of fine differences is inconvenient, especially on color displays. If that is the case, type * with a negative prefix argument. This unhighlights fine differences for the current region.
To unhighlight fine differences in all difference regions, use the command @. Repeated typing of this key cycles through three different states: auto-refining, no-auto-refining, and no-highlighting of fine differences.
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This section describes variables that specify the programs to be used for applying patches and for computing the main difference regions (not the fine difference regions):
ediff-diff-program
ediff-diff3-program
ediff-diff-options
ediff-diff3-options
In ediff-diff-options
, it may be useful to specify options
such as `-w' that ignore certain kinds of changes. However,
Ediff does not let you use the option `-c', as it doesn't recognize this
format yet.
ediff-coding-system-for-read
diff3
and diff
send to Emacs. The default
is raw-text
, and this should work fine in Unix and in most
cases under Windows NT/95/98/2000. There are diff
programs
for which the default option doesn't work under Windows. In such cases,
raw-text-dos
might work. If not, you will have to experiment with
other coding systems or use GNU diff.
ediff-patch-program
ediff-patch-options
, ediff-backup-specs
, and
ediff-backup-extension
as described below.
ediff-patch-options
ediff-patch-program
.
Note: the `-b' and `-z' options should be specified in
`ediff-backup-specs', not in ediff-patch-options
.
It is recommended to pass the `-f' option to the patch program, so it won't ask questions. However, some implementations don't accept this option, in which case the default value of this variable should be changed.
ediff-backup-extension
ediff-backup-specs
is given.
ediff-backup-specs
Some versions of the patch program let the user specify `-b backup-extension'. Other versions only permit `-b', which (usually) assumes the extension `.orig'. Yet others force you to use `-z<backup-extension>'.
Note that both `ediff-backup-extension' and `ediff-backup-specs' must be properly set. If your patch program takes the option `-b', but not `-b extension', the variable `ediff-backup-extension' must still be set so Ediff will know which extension to use.
ediff-custom-diff-program
ediff-custom-diff-options
diff
program, it partially makes up for this drawback by letting you save the
output from diff
in your preferred format, which is specified via
the above two variables.
The output generated by ediff-custom-diff-program
(which doesn't
even have to be a standard-style diff
!) is not used by Ediff. It is
provided exclusively so that you can
refer to
it later, send it over email, etc. For instance, after reviewing the
differences, you may want to send context differences to a colleague.
Since Ediff ignores the `-c' option in
ediff-diff-program
, you would have to run diff -c
separately
just to produce the list of differences. Fortunately,
ediff-custom-diff-program
and ediff-custom-diff-options
eliminate this nuisance by keeping a copy of a difference list in the
desired format in a buffer that can be displayed via the command D.
ediff-patch-default-directory
Warning: Ediff does not support the output format of VMS
diff
. Instead, make sure you are using some implementation of POSIX
diff
, such as gnudiff
.
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Ediff supports three-way comparison via the functions ediff-files3
and
ediff-buffers3
. The interface is the same as for two-way comparison.
In three-way comparison and merging, Ediff reports if any two difference
regions are identical. For instance, if the current region in buffer A
is the same as the region in buffer C, then the mode line of buffer A will
display `[=diff(C)]' and the mode line of buffer C will display
`[=diff(A)]'.
Merging is done according to the following algorithm.
If a difference region in one of the buffers, say B, differs from the ancestor file while the region in the other buffer, A, doesn't, then the merge buffer, C, gets B's region. Similarly when buffer A's region differs from the ancestor and B's doesn't, A's region is used.
If both regions in buffers A and B differ from the ancestor file, Ediff
chooses the region according to the value of the variable
ediff-default-variant
. If its value is default-A
then A's
region is chosen. If it is default-B
then B's region is chosen.
If it is combined
then the region in buffer C will look like
this:
<<<<<<< variant A the difference region from buffer A >>>>>>> variant B the difference region from buffer B ####### Ancestor the difference region from the ancestor buffer, if available ======= end |
The above is the default template for the combined region. The user can
customize this template using the variable
ediff-combination-pattern
.
The variable ediff-combination-pattern
specifies the template that
determines how the combined merged region looks like. The template is
represented as a list of the form (STRING1 Symbol1 STRING2 Symbol2
STRING3 Symbol3 STRING4)
. The symbols here must be atoms of the form
A
, B
, or Ancestor
. They determine the order in which
the corresponding difference regions (from buffers A, B, and the ancestor
buffer) are displayed in the merged region of buffer C. The strings in the
template determine the text that separates the aforesaid regions. The
default template is
("<<<<<<< variant A" A ">>>>>>> variant B" B "####### Ancestor" Ancestor "======= end") |
(this is one long line) and the corresponding combined region is shown above. The order in which the regions are shown (and the separator strings) can be changed by changing the above template. It is even possible to add or delete region specifiers in this template (although the only possibly useful such modification seems to be the deletion of the ancestor).
In addition to the state of the difference, Ediff displays the state of the
merge for each region. If a difference came from buffer A by default
(because both regions A and B were different from the ancestor and
ediff-default-variant
was set to default-A
) then
`[=diff(A) default-A]' is displayed in the mode line. If the
difference in buffer C came, say, from buffer B because the difference
region in that buffer differs from the ancestor, but the region in buffer A
does not (if merging with an ancestor) then `[=diff(B) prefer-B]' is
displayed. The indicators default-A/B and prefer-A/B are inspired by
Emerge and have the same meaning.
Another indicator of the state of merge is `combined'. It appears with any difference region in buffer C that was obtained by combining the difference regions in buffers A and B as explained above.
In addition to the state of merge and state of difference indicators, while merging with an ancestor file or buffer, Ediff informs the user when the current difference region in the (normally invisible) ancestor buffer is empty via the AncestorEmpty indicator. This helps determine if the changes made to the original in variants A and B represent pure insertion or deletion of text: if the mode line shows AncestorEmpty and the corresponding region in buffers A or B is not empty, this means that new text was inserted. If this indicator is not present and the difference regions in buffers A or B are non-empty, this means that text was modified. Otherwise, the original text was deleted.
Although the ancestor buffer is normally invisible, Ediff maintains difference regions there and advances the current difference region accordingly. All highlighting of difference regions is provided in the ancestor buffer, except for the fine differences. Therefore, if desired, the user can put the ancestor buffer in a separate frame and watch it there. However, on a TTY, only one frame can be visible at any given time, and Ediff doesn't support any single-frame window configuration where all buffers, including the ancestor buffer, would be visible. However, the ancestor buffer can be displayed by typing / to the control window. (Type C-l to hide it again.)
Note that the state-of-difference indicators `=diff(A)' and `=diff(B)' above are not redundant, even in the presence of a state-of-merge indicator. In fact, the two serve different purposes.
For instance, if the mode line displays `=diff(B) prefer(B)' and you copy a difference region from buffer A to buffer C then `=diff(B)' will change to `diff-A' and the mode line will display `=diff(A) prefer-B'. This indicates that the difference region in buffer C is identical to that in buffer A, but originally buffer C's region came from buffer B. This is useful to know because you can recover the original difference region in buffer C by typing r.
Ediff never changes the state-of-merge indicator, except in response to the ! command (see below), in which case the indicator is lost. On the other hand, the state-of-difference indicator is changed automatically by the copying/recovery commands, a, b, r, +.
The ! command loses the information about origins of the regions
in the merge buffer (default-A, prefer-B, or combined). This is because
recomputing differences in this case means running diff3
on
buffers A, B, and the merge buffer, not on the ancestor buffer. (It
makes no sense to recompute differences using the ancestor file, since
in the merging mode Ediff assumes that you have not edited buffers A and
B, but that you may have edited buffer C, and these changes are to be
preserved.) Since some difference regions may disappear as a result of
editing buffer C and others may arise, there is generally no simple way
to tell where the various regions in the merge buffer came from.
In three-way comparison, Ediff tries to disregard regions that consist entirely of white space. For instance, if, say, the current region in buffer A consists of the white space only (or if it is empty), Ediff will not take it into account for the purpose of computing fine differences. The result is that Ediff can provide a better visual information regarding the actual fine differences in the non-white regions in buffers B and C. Moreover, if the regions in buffers B and C differ in the white space only, then a message to this effect will be displayed.
In the merge mode, the share of the split between window C (the window
displaying the merge-buffer) and the windows displaying buffers A and B
is controlled by the variable ediff-merge-window-share
. Its
default value is 0.5. To make the merge-buffer window smaller, reduce
this amount.
We don't recommend increasing the size of the merge-window to more than
half the frame (i.e., to increase the value of
ediff-merge-window-share
) to more than 0.5, since it would be
hard to see the contents of buffers A and B.
You can temporarily shrink the merge window to just one line by typing s. This change is temporary, until Ediff finds a reason to redraw the screen. Typing s again restores the original window size.
With a positive prefix argument, the s command will make the merge window slightly taller. This change is persistent. With `-' or with a negative prefix argument, the command s makes the merge window slightly shorter. This change also persistent.
Ediff lets you automatically ignore the regions where only one of the
buffers A and B disagrees with the ancestor. To do this, set the
variable ediff-show-clashes-only
to non-nil
.
You can toggle this feature interactively by typing $$.
Note that this variable affects only the show next/previous difference commands. You can still jump directly to any difference region directly using the command j (with a prefix argument specifying the difference number).
The variable ediff-autostore-merges
controls what happens to the
merge buffer when Ediff quits. If the value is nil
, nothing is done
to the merge buffer--it will be the user's responsibility to save it.
If the value is t
, the user will be asked where to save the buffer
and whether to delete it afterwards. It the value is neither nil
nor
t
, the merge buffer is saved only if this merge session was
invoked from a group of related Ediff session, such as those that result
from ediff-merge-directories
,
ediff-merge-directory-revisions
, etc.
See section 5. Session Groups. This behavior is implemented in the function
ediff-maybe-save-and-delete-merge
, which is a hook in
ediff-quit-merge-hook
. The user can supply a different hook, if
necessary.
The variable ediff-autostore-merges
is buffer-local, so it can be
set in a per-buffer manner. Therefore, use setq-default
to globally
change this variable.
When merge buffers are saved automatically as directed by
ediff-autostore-merges
, Ediff attaches a prefix to each file, as
specified by the variable ediff-merge-filename-prefix
. The default
is merge_
, but this can be changed by the user.
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Ediff supports version control and lets you compare versions of files
visited by Emacs buffers via the function ediff-revision
. This
feature is controlled by the following variables:
ediff-version-control-package
If you are like most Emacs users, Ediff will use VC as the version control package. This is the standard Emacs interface to RCS, CVS, and SCCS.
However, if your needs are better served by other interfaces, you will have to tell Ediff which version control package you are using, e.g.,
(setq ediff-version-control-package 'rcs) |
Apart from the standard `vc.el', Ediff supports three other interfaces to version control: `rcs.el', `pcl-cvs.el' (recently renamed pcvs.el), and `generic-sc.el'. The package `rcs.el' is written by Sebastian Kremer <sk@thp.Uni-Koeln.DE> and is available as
`ftp.cs.buffalo.edu:pub/Emacs/rcs.tar.Z' `ftp.uni-koeln.de:/pub/gnu/emacs/rcs.tar.Z' |
Ediff's interface to the above packages allows the user to compare the versions of the current buffer or to merge them (with or without an ancestor-version). These operations can also be performed on directories containing files under version control.
In case of `pcl-cvs.el', Ediff can also be invoked via the function
run-ediff-from-cvs-buffer
---see the documentation string for this
function.
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When Ediff is running, the mode line of `Ediff Control Panel' buffer shows the current difference number and the total number of difference regions in the two files.
The mode line of the buffers being compared displays the type of the
buffer (`A:', `B:', or `C:') and (usually) the file name.
Ediff tries to be intelligent in choosing the mode line buffer
identification. In particular, it works well with the
`uniquify.el' and `mode-line.el' packages (which improve on
the default way in which Emacs displays buffer identification). If you
don't like the way Ediff changes the mode line, you can use
ediff-prepare-buffer-hook
to modify the mode line.
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Here are a few other variables for customizing Ediff:
ediff-split-window-function
split-window-vertically
, but you can set it to
split-window-horizontally
, if you so wish.
Ediff also lets you switch from vertical to horizontal split and back
interactively.
Note that if Ediff detects that all the buffers it compares are displayed in separate frames, it assumes that the user wants them to be so displayed and stops splitting windows. Instead, it arranges for each buffer to be displayed in a separate frame. You can switch to the one-frame mode by hiding one of the buffers A/B/C.
You can also swap the windows where buffers are displayed by typing ~.
ediff-merge-split-window-function
ediff-split-window-function
, but it defaults
to split-window-horizontally
instead of
split-window-vertically
.
ediff-make-wide-display-function
ediff-make-wide-display-function
for details. It is also
recommended to look into the source of the default function
ediff-make-wide-display
.
You can toggle wide/regular display by typing m. In the wide display mode, buffers A, B (and C, when applicable) are displayed in a single frame that is as wide as the entire workstation screen. This is useful when files are compared side-by-side. By default, the display is widened without changing its height.
ediff-use-last-dir
nil
,
Ediff uses the default directory of the current buffer when it
prompts the user for file names. Otherwise, it will use the
directories it had previously used for files A, B, or C, respectively.
ediff-no-emacs-help-in-control-buffer
t
, makes C-h
behave like the DEL key, i.e., it will move you back to the previous
difference rather than invoking help. This is useful when, in an xterm
window or a text-only terminal, the Backspace key is bound to C-h and is
positioned more conveniently than the DEL key.
ediff-toggle-read-only-function
The default function that Ediff uses simply toggles the read-only property, unless the file is under version control. For a checked-in file under version control, Ediff first tries to check the file out.
ediff-make-buffers-readonly-at-startup nil
t
, all variant buffers are made read-only at Ediff startup.
ediff-keep-variants
t
, meaning that the buffers being compared or merged will
be preserved when Ediff quits. Setting this to nil
causes Ediff to
offer the user a chance to delete these buffers (if they are not modified).
Supplying a prefix argument to the quit command (q
) temporarily
reverses the meaning of this variable. This is convenient when the user
prefers one of the behaviors most of the time, but occasionally needs the
other behavior.
However, Ediff temporarily resets this variable to t
if it is
invoked via one of the "buffer" jobs, such as ediff-buffers
.
This is because it is all too easy to loose day's work otherwise.
Besides, in a "buffer" job, the variant buffers have already been loaded
prior to starting Ediff, so Ediff just preserves status quo here.
Using ediff-cleanup-hook
, one can make Ediff delete the variants
unconditionally (e.g., by making ediff-janitor
into one of these hooks).
ediff-keep-tmp-versions
nil
. If t
, the versions of the files being
compared or merged using operations such as ediff-revision
or
ediff-merge-revisions
are not deleted on exit. The normal action is
to clean up and delete these version files.
ediff-grab-mouse
t
. Normally, Ediff grabs mouse and puts it in its
control frame. This is useful since the user can be sure that when he
needs to type an Ediff command the focus will be in an appropriate Ediff's
frame. However, some users prefer to move the mouse by themselves. The
above variable, if set to maybe
, will prevent Ediff from grabbing
the mouse in many situations, usually after commands that may take more
time than usual. In other situation, Ediff will continue grabbing the mouse
and putting it where it believes is appropriate. If the value is
nil
, then mouse is entirely user's responsibility.
Try different settings and see which one is for you.
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Some users need to customize Ediff in rather sophisticated ways, which
requires different defaults for different kinds of files (e.g., SGML,
etc.). Ediff supports this kind of customization in several ways. First,
most customization variables are buffer-local. Those that aren't are
usually accessible from within Ediff Control Panel, so one can make them
local to the panel by calling make-local-variable from within
ediff-startup-hook
.
Second, the function ediff-setup
accepts an optional sixth
argument which has the form ((var-name-1 . val-1)
(var-name-2 . val-2) ...)
. The function
ediff-setup
sets the variables in the list to the respective
values, locally in the Ediff control buffer. This is an easy way to
throw in custom variables (which usually should be buffer-local) that
can then be tested in various hooks.
Make sure the variable ediff-job-name
and ediff-word-mode
are set
properly in this case, as some things in Ediff depend on this.
Finally, if you want custom-tailored help messages, you can set the
variables ediff-brief-help-message-function
and
ediff-long-help-message-function
to functions that return help strings.
When customizing Ediff, some other variables are useful, although they are
not user-definable. They are local to the Ediff control buffer, so this
buffer must be current when you access these variables. The control buffer
is accessible via the variable ediff-control-buffer
, which is also
local to that buffer. It is usually used for checking if the current buffer
is also the control buffer.
Other variables of interest are:
ediff-buffer-A
ediff-buffer-B
ediff-buffer-C
nil
.
ediff-window-A
nil
or it may be a dead window.
ediff-window-B
ediff-window-C
ediff-control-frame
nil
only if Ediff uses the multiframe display, i.e., when
the control buffer is in its own frame.
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