diff options
Diffstat (limited to 'doc/misc/ses.texi')
| -rw-r--r-- | doc/misc/ses.texi | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/doc/misc/ses.texi b/doc/misc/ses.texi index 58f9ba8ccf3..8b0bb82f174 100644 --- a/doc/misc/ses.texi +++ b/doc/misc/ses.texi @@ -444,6 +444,36 @@ printer function. Then, if you call again @code{"%.3f"}, all the cells using printer @samp{foo} will be reprinted accordingly. +When you define a printer function with a lambda expression taking one +argument, please take care that the returned value is a string, or a +list containing a string, even when the input argument has an +unexpected value. Here is an example: + +@example +(lambda (val) + (cond + ((null val) "") + ((and (numberp val) (>= val 0)) (format "%.1f" val)) + (t (ses-center-span (format "%S" val) ?#)))) +@end example + +This example will: +@itemize +@item +When the cell is empty (ie.@: when @code{val} is @code{nil}), print an +empty string @code{""} +@item +When the cell value is a non negative number, format the the value in +fixed-point notation with one decimal after point +@item +Otherwise, handle the value as erroneous by printing it as an +s-expression (using @code{prin1}), centered and surrounded by @code{#} +filling. +@end itemize + + + + @node Clearing cells @section Clearing cells @cindex clearing commands |