bug#69666: [PATCH] (vtable-update-object): Make old-object argument optional

[Adam Porter <adam@alphapapa.net>]

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Hi,

Please see the attached patch which makes `vtable-update-object' easier 
to use in the common case of updating an existing object's 
representation in a table (rather than replacing it with another object).

Thanks,
Adam

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From ebb5a2a6ea5bc0437fd39d0e87406fe723183e5a Mon Sep 17 00:00:00 2001
From: Adam Porter <adam@alphapapa.net>
Date: Fri, 8 Mar 2024 23:43:14 -0600
Subject: [PATCH] (vtable-update-object): Make old-object argument optional

* lisp/emacs-lisp/vtable.el (vtable-update-object): Make 'old-object'
argument optional.
* doc/misc/vtable.texi (Interface Functions): Update documentation.

It's often necessary to update the representation of a single object in
a table (e.g a struct, whose identity does not change when its slots'
values are changed).  To do so, now the function may be called like
this:

  (vtable-update-object table foo)

Instead of like this:

  (vtable-update-object table foo foo)
---
 doc/misc/vtable.texi      | 7 ++++---
 lisp/emacs-lisp/vtable.el | 7 +++++--
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/doc/misc/vtable.texi b/doc/misc/vtable.texi
index a4f2ed29d93..f6a2ae05818 100644
--- a/doc/misc/vtable.texi
+++ b/doc/misc/vtable.texi
@@ -554,9 +554,10 @@ Interface Functions
 also updates the displayed table.
 @end defun
 
-@defun vtable-update-object table object old-object
-Change @var{old-object} into @var{object} in @var{table}.  This also
-updates the displayed table.
+@defun vtable-update-object table object &optional old-object
+Change @var{old-object} into @var{object} in @var{table}; or, without
+@var{old-object}, update existing @var{object} in @var{table}.  This
+also updates the displayed table.
 
 This has the same effect as calling @code{vtable-remove-object} and
 then @code{vtable-insert-object}, but is more efficient.
diff --git a/lisp/emacs-lisp/vtable.el b/lisp/emacs-lisp/vtable.el
index 02020552e7f..ae6a5296cef 100644
--- a/lisp/emacs-lisp/vtable.el
+++ b/lisp/emacs-lisp/vtable.el
@@ -283,8 +283,11 @@ vtable-goto-column
       (goto-char (prop-match-beginning match))
     (end-of-line)))
 
-(defun vtable-update-object (table object old-object)
-  "Replace OLD-OBJECT in TABLE with OBJECT."
+(defun vtable-update-object (table object &optional old-object)
+  "Replace OLD-OBJECT in TABLE with OBJECT.
+Without OLD-OBJECT, just update existing OBJECT in TABLE."
+  (unless old-object
+    (setq old-object object))
   (let* ((objects (vtable-objects table))
          (inhibit-read-only t))
     ;; First replace the object in the object storage.
-- 
2.30.2