Re: Gradually replacing INITIAL-INPUT in minibuffer

[Arash Esbati]

Hi all,

Tassilo Horn <tsdh@gnu.org> writes:

> Arash Esbati <arash@gnu.org> writes:
>
>> Before touching the rest, I like to discuss this here and hear from
>> users and developers what they think.
>
> Yes, please. :-)

This is my idea on this: We add an additional argument `default' to the
respective functions.  Here an example for `TeX-arg-length':

--8<---------------cut here---------------start------------->8---
diff --git a/latex.el b/latex.el
index bfd5b8c6..549d4ca9 100644
--- a/latex.el
+++ b/latex.el
@@ -2222,25 +2222,32 @@ list of defined saveboxes."
         (LaTeX-add-saveboxes savebox))
     (TeX-argument-insert savebox optional TeX-esc)))

-(defun TeX-arg-length (optional &optional prompt initial-input definition)
+(defun TeX-arg-length (optional &optional prompt initial-input definition 
default)
   "Prompt for a LaTeX length.
 If OPTIONAL is non-nil, insert the resulting value as an optional
 argument, otherwise as a mandatory one.  Use PROMPT as the prompt
 string.  If INITIAL-INPUT is non-nil, insert it in the minibuffer
 initially, with point positioned at the end.  If DEFINITION is
-non-nil, the length is added to the list of defined length."
-  (let ((length (completing-read (TeX-argument-prompt optional prompt "Length")
-                                 ;; A valid length can be a macro or a length 
of
-                                 ;; the form <value><dimension>.  Input 
starting
-                                 ;; with a `\' can be completed with length
-                                 ;; macros.
-                                 (mapcar (lambda(elt) (concat TeX-esc (car 
elt)))
-                                         (LaTeX-length-list))
-                                 ;; Some macros takes as argument only a length
-                                 ;; macro (e.g., `\setlength' in its first
-                                 ;; argument, and `\newlength'), in this case 
is
-                                 ;; convenient to set `\\' as initial input.
-                                 nil nil initial-input)))
+non-nil, the length is added to the list of defined length.
+DEFAULT is passed to `completing-read', which see."
+  (let ((length (completing-read
+                 (TeX-argument-prompt optional prompt
+                                      (if (and default (not optional))
+                                          (concat "Length (default "
+                                                  default
+                                                  ")")
+                                        "Length"))
+                 ;; A valid length can be a macro or a length of
+                 ;; the form <value><dimension>.  Input starting
+                 ;; with a `\' can be completed with length
+                 ;; macros.
+                 (mapcar (lambda(elt) (concat TeX-esc (car elt)))
+                         (LaTeX-length-list))
+                 ;; Some macros takes as argument only a length
+                 ;; macro (e.g., `\setlength' in its first
+                 ;; argument, and `\newlength'), in this case is
+                 ;; convenient to set `\\' as initial input.
+                 nil nil initial-input nil default)))
     (if (and definition (not (zerop (length length))))
         ;; Strip leading TeX-esc from macro name
         (LaTeX-add-lengths (substring length 1)))
--8<---------------cut here---------------end--------------->8---

The call in a style would change from

  (TeX-arg-length "Width" "1.0\\linewidth")

to

  (TeX-arg-length "Width" nil nil "1.0\\linewidth")

Note that the default value is considered only with a mandatory
argument.

One question: Is there a more elegant way to construct the prompt?

Any comments welcome.

Best, Arash