Commit 2e00781a authored by Richard M. Stallman's avatar Richard M. Stallman
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entered into RCS

parent 742f715d
......@@ -60,7 +60,7 @@ saving the buffer the first time.
This buffer-local variable indicates whether this buffer's file has
been backed up on account of this buffer. If it is non-@code{nil}, then
the backup file has been written. Otherwise, the file should be backed
up when it is next saved (if backup files are enabled). This is a
up when it is next saved (if backups are enabled). This is a
permanent local; @code{kill-local-variables} does not alter it.
@end defvar
......@@ -86,12 +86,12 @@ which may save disk space. (You would put this code in your
@end smallexample
@end defopt
@defvar backup-enable-predicate filename
@defvar backup-enable-predicate
This variable's value is a function to be called on certain occasions to
decide whether a there should be backup files for file name
@var{filename}. If it returns @code{nil}, backups are disabled.
Otherwise, the other variables in this section say whether and how to
make backups.
decide whether a file should have backup files. The function receives
one argument, a file name to consider. If the function returns
@code{nil}, backups are disabled for that file. Otherwise, the other
variables in this section say whether and how to make backups.
The default value is this:
......@@ -107,8 +107,11 @@ The default value is this:
If this variable is non-@code{nil}, backups are inhibited. It records
the result of testing @code{backup-enable-predicate} on the visited file
name. It can also coherently be used by other mechanisms that inhibit
backups based on which file is visited. Major modes should not set this
variable.
backups based on which file is visited. This is a permanent local,
so that changing the major mode does not lose its value.
Major modes should not set this variable---they should set
@code{make-backup-files} instead.
@end defvar
@node Rename or Copy
......@@ -194,16 +197,16 @@ otherwise, do not.
Do not make numbered backups.
@item @var{anything else}
Do make numbered backups.
Make numbered backups.
@end table
@end defopt
The use of numbered backups ultimately leads to a large number of
backup versions, which must then be deleted. Emacs can do this
automatically.
automatically or it can ask the user whether to delete them.
@defopt kept-new-versions
The value of this variable is the number of oldest versions to keep
The value of this variable is the number of newest versions to keep
when a new numbered backup is made. The newly made backup is included
in the count. The default value is 2.
@end defopt
......@@ -216,7 +219,7 @@ when a new numbered backup is made. The default value is 2.
If there are backups numbered 1, 2, 3, 5, and 7, and both of these
variables have the value 2, then the backups numbered 1 and 2 are kept
as old versions and those numbered 5 and 7 are kept as new versions;
backup version 3 is deleted. The function @code{find-backup-file-name}
backup version 3 is excess. The function @code{find-backup-file-name}
(@pxref{Backup Names}) is responsible for determining which backup
versions to delete, but does not delete them itself.
......@@ -229,7 +232,7 @@ them.
@defopt dired-kept-versions
This variable specifies how many of the newest backup versions to keep
in the Dired command @kbd{.} (@code{dired-clean-directory}). That's the
same thing @code{kept-new-versions} does when you make a new backup
same thing @code{kept-new-versions} specifies when you make a new backup
file. The default value is 2.
@end defopt
......@@ -278,7 +281,7 @@ to redefine for customization.
@end defun
@defun make-backup-file-name filename
This function returns a string which is the name to use for a
This function returns a string that is the name to use for a
non-numbered backup file for file @var{filename}. On Unix, this is just
@var{filename} with a tilde appended.
......@@ -293,9 +296,9 @@ The standard definition of this function is as follows:
@end group
@end smallexample
You can change the backup file naming convention by redefining this
You can change the backup-file naming convention by redefining this
function. The following example redefines @code{make-backup-file-name}
to prepend a @samp{.} as well as appending a tilde:
to prepend a @samp{.} in addition to appending a tilde:
@smallexample
@group
......@@ -337,10 +340,10 @@ version that the caller should consider deleting now.
@c Emacs 19 feature
@defun file-newest-backup filename
This function returns the name of the most recent backup file for
@var{filename}, or @code{nil} that file has no backup files.
@var{filename}, or @code{nil} if that file has no backup files.
Some file comparison commands use this function in order to compare
a file by default with its most recent backup.
Some file comparison commands use this function so that they can
automatically compare a file with its most recent backup.
@end defun
@node Auto-Saving
......@@ -419,8 +422,8 @@ correspondingly.
This function returns the file name to use for auto-saving the current
buffer. This is just the file name with hash marks (@samp{#}) appended
and prepended to it. This function does not look at the variable
@code{auto-save-visited-file-name}; you should check that before calling
this function.
@code{auto-save-visited-file-name} (described below); you should check
that before calling this function.
@example
@group
......@@ -458,7 +461,7 @@ change @code{auto-save-file-name-p} in a corresponding way.
@defvar auto-save-visited-file-name
If this variable is non-@code{nil}, Emacs auto-saves buffers in
the files they are visiting. That is, the auto-save is done in the same
file which you are editing. Normally, this variable is @code{nil}, so
file that you are editing. Normally, this variable is @code{nil}, so
auto-save files have distinct names that are created by
@code{make-auto-save-file-name}.
......@@ -535,15 +538,15 @@ nothing.
@end defun
@defvar buffer-saved-size
The value of this buffer-local variable is the former length of the
current buffer, as of the last time it was read in, saved or auto-saved.
This is used to detect a substantial decrease in size, and turn off
auto-saving in response.
The value of this buffer-local variable is the length of the current
buffer as of the last time it was read in, saved, or auto-saved. This is
used to detect a substantial decrease in size, and turn off auto-saving
in response.
If it is -1, that means auto-saving is temporarily shut off in this
buffer due to a substantial deletion. Explicitly saving the buffer
stores a positive value in this variable, thus reenabling auto-save.
Turning Auto-Save mode off or on also alters this variable.
Turning auto-save mode off or on also alters this variable.
@end defvar
@node Reverting
......@@ -571,33 +574,34 @@ the buffer; but if the argument @var{noconfirm} is non-@code{nil},
@code{revert-buffer} does not ask for confirmation.
Reverting tries to preserve marker positions in the buffer by using the
replacement feature of @code{insert-file-contents}. If there is no
actual difference between the buffer and the file, before reversion,
this preserves all the markers. If reversion does change the buffer,
this preserves the markers in the unchanged text (if any) at the
beginning and end of the buffer. Preserving any additional markers
would be problematical.
If the value of the @code{revert-buffer-function} variable is
non-@code{nil}, it is called as a function with no arguments to do the
work.
replacement feature of @code{insert-file-contents}. If the buffer
contents and the file contents are identical before the revert
operation, reverting preserves all the markers. If they are not
identical, reverting does change the buffer; then it preserves the
markers in the unchanged text (if any) at the beginning and end of the
buffer. Preserving any additional markers would be problematical.
@end deffn
You can customize how @code{revert-buffer} does its work by setting
these variables---typically, as buffer-local variables.
@defvar revert-buffer-function
The value of this variable is the function to use to revert this
buffer; but if the value of this variable is @code{nil}, then the
@code{revert-buffer} function carries out its default action. Modes
such as Dired mode, in which the text being edited does not consist of a
file's contents but can be regenerated in some other fashion, give this
variable a buffer-local value that is a function to regenerate the
contents.
The value of this variable is the function to use to revert this buffer.
If non-@code{nil}, it is called as a function with no arguments to do
the work of reverting. If the value is @code{nil}, reverting works the
usual way.
Modes such as Dired mode, in which the text being edited does not
consist of a file's contents but can be regenerated in some other
fashion, give this variable a buffer-local value that is a function to
regenerate the contents.
@end defvar
@defvar revert-buffer-insert-file-contents-function
The value of this variable, if non-@code{nil}, is the function to use
to insert contents when reverting this buffer. The function receives
two arguments, first the file name to use, and second, @code{t} if the
user has asked to read the auto-save file.
The value of this variable, if non-@code{nil}, is the function to use to
insert contents when reverting this buffer. The function receives two
arguments, first the file name to use; second, @code{t} if the user has
asked to read the auto-save file.
@end defvar
@defvar before-revert-hook
......
......@@ -3,7 +3,7 @@
@c Copyright (C) 1990, 1991, 1992, 1993, 1994 Free Software Foundation, Inc.
@c See the file elisp.texi for copying conditions.
@setfilename ../info/debugging
@node Debugging, Streams, Byte Compilation, Top
@node Debugging, Read and Print, Byte Compilation, Top
@chapter Debugging Lisp Programs
There are three ways to investigate a problem in an Emacs Lisp program,
......
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