Add `string-pad'

* doc/lispref/strings.texi (Creating Strings): Document it.
* lisp/emacs-lisp/shortdoc.el (string): Add example.

* lisp/emacs-lisp/subr-x.el (string-pad): New function.

1 files changed, 9 insertions, 0 deletions

diff --git a/doc/lispref/strings.texi b/doc/lispref/strings.texi
index e4ca2617512..958ae4c0a15 100644
--- a/doc/lispref/strings.texi
+++ b/doc/lispref/strings.texi
@@ -419,6 +419,15 @@ Split @var{string} into a list of strings on newline boundaries.  If
 @var{omit-nulls}, remove empty lines from the results.
 @end defun
 
+@defun string-pad string length &optional padding
+Pad @var{string} to the be of @var{length} using @var{padding} as the
+padding character (defaulting to the space character).  If
+@var{string} is shorter than @var{length}, no padding is done.  If
+@var{length} is positive, the padding is done to the end of the
+string, and if it's negative, to the start of the string (using the
+absolute value).
+@end defun
+
 @node Modifying Strings
 @section Modifying Strings
 @cindex modifying strings