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Diffstat (limited to 'lispref/commands.texi')
| -rw-r--r-- | lispref/commands.texi | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/lispref/commands.texi b/lispref/commands.texi index a75c0c89fec..e494d0dfc5a 100644 --- a/lispref/commands.texi +++ b/lispref/commands.texi @@ -233,6 +233,20 @@ reading the keyboard input: (let ((string (read-string "Foo: " nil 'my-history))) (list (region-beginning) (region-end) string))) @end smallexample + +@strong{Warning:} the argument values should not include any data +types that can't be printed and then read. Some facilities save +@code{command-history} in a file to be read in the subsequent +sessions; if a command's arguments contain a data type that prints +using @samp{#<@dots{}>} syntax, those facilities won't work. + +There are, however, a few exceptions: it is ok to use a limited set of +expressions such as @code{(point)}, @code{(mark)}, +@code{(region-beginning)}, and @code{(region-end)}, because Emacs +recognizes them specially and puts the expression (rather than its +value) into the command history. To see whether the expression you +wrote is one of these exceptions, run the command, then examine +@code{(car command-history)}. @end itemize @cindex examining the @code{interactive} form |