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Clarify command loop's role in undo boundary (Bug#2433).

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* text.texi (Undo): Clarify command loop behavior (Bug#2433).
* commands.texi (Command Overview): Mention undo-boundary call.
This commit is contained in:
Chong Yidong 2010-06-24 15:05:47 -04:00
parent 62e034c228
commit 51422d6dde
3 changed files with 29 additions and 17 deletions
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6
doc/lispref/ChangeLog
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@ -1,3 +1,9 @@
2010-06-24 Chong Yidong <cyd@stupidchicken.com>
* text.texi (Undo): Clarify command loop behavior (Bug#2433).
* commands.texi (Command Overview): Mention undo-boundary call.
2010-06-23 Glenn Morris <rgm@gnu.org>
* abbrevs.texi, commands.texi, compile.texi, debugging.texi:

23
doc/lispref/commands.texi
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@ -53,16 +53,19 @@ function. If the key is @kbd{M-x}, then it reads the name of another
command, which it then calls. This is done by the command
@code{execute-extended-command} (@pxref{Interactive Call}).
To execute a command requires first reading the arguments for it.
This is done by calling @code{command-execute} (@pxref{Interactive
Call}). For commands written in Lisp, the @code{interactive}
specification says how to read the arguments. This may use the prefix
argument (@pxref{Prefix Command Arguments}) or may read with prompting
in the minibuffer (@pxref{Minibuffers}). For example, the command
@code{find-file} has an @code{interactive} specification which says to
read a file name using the minibuffer. The command's function body does
not use the minibuffer; if you call this command from Lisp code as a
function, you must supply the file name string as an ordinary Lisp
Prior to executing the command, Emacs runs @code{undo-boundary} to
create an undo boundary. @xref{Maintaining Undo}.
To execute a command, Emacs first reads its arguments by calling
@code{command-execute} (@pxref{Interactive Call}). For commands
written in Lisp, the @code{interactive} specification says how to read
the arguments. This may use the prefix argument (@pxref{Prefix
Command Arguments}) or may read with prompting in the minibuffer
(@pxref{Minibuffers}). For example, the command @code{find-file} has
an @code{interactive} specification which says to read a file name
using the minibuffer. The function body of @code{find-file} does not
use the minibuffer, so if you call @code{find-file} as a function from
Lisp code, you must supply the file name string as an ordinary Lisp
function argument.
If the command is a string or vector (i.e., a keyboard macro) then

17
doc/lispref/text.texi
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@ -1299,13 +1299,16 @@ This function places a boundary element in the undo list. The undo
command stops at such a boundary, and successive undo commands undo
to earlier and earlier boundaries. This function returns @code{nil}.
The editor command loop automatically creates an undo boundary before
each key sequence is executed. Thus, each undo normally undoes the
effects of one command. Self-inserting input characters are an
exception. The command loop makes a boundary for the first such
character; the next 19 consecutive self-inserting input characters do
not make boundaries, and then the 20th does, and so on as long as
self-inserting characters continue.
The editor command loop automatically calls @code{undo-boundary} just
before executing each key sequence, so that each undo normally undoes
the effects of one command. As an exception, the command
@code{self-insert-command}, which produces self-inserting input
characters (@pxref{Commands for Insertion}), may remove the boundary
inserted by the command loop: a boundary is accepted for the first
such character, the next 19 consecutive self-inserting input
characters do not have boundaries, and then the 20th does; and so on
as long as the self-inserting characters continue. Hence, sequences
of consecutive character insertions can be undone as a group.
All buffer modifications add a boundary whenever the previous undoable
change was made in some other buffer. This is to ensure that