bug#29923: [PATCH] Skip writing empty abbrev tables

[Allen Li <darkfeline@felesatra.moe>]

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On Sun, Sep 9, 2018 at 1:43 PM Noam Postavsky <npostavs@gmail.com> wrote:
>
> Allen Li <vianchielfaura@gmail.com> writes:
>
> > Subject: [PATCH] Skip writing empty abbrev tables
> >
> > Fixes bug#29923
> >
> > * lisp/abbrev.el (write-abbrev-file): Pass SKIPEMPTY to
> > insert-abbrev-table-description.
> > (insert-abbrev-table-description): Add SKIPEMPTY optional
> > parameter. Skip inserting empty tables if SKIPEMPTY is non-nil.
>
>
> >  (eval-when-compile (require 'cl-lib))
> >  (require 'obarray)
> > +(require 'seq)
>
> You didn't end up using seq, as far as I can tell.

Thanks, removed.

>
> > -(defun insert-abbrev-table-description (name &optional readable)
> > +(defun insert-abbrev-table-description (name &optional readable skipempty)
> >    "Insert before point a full description of abbrev table named NAME.
> >  NAME is a symbol whose value is an abbrev table.
> >  If optional 2nd arg READABLE is non-nil, a human-readable description
> >  is inserted.  Otherwise the description is an expression,
> >  a call to `define-abbrev-table', which would
> >  define the abbrev table NAME exactly as it is currently defined.
> > +If optional arg SKIPEMPTY is non-nil, skip insertion if table is empty.
> >
> >  Abbrevs marked as \"system abbrevs\" are omitted."
>
> > -    (mapatoms (lambda (sym) (if (symbol-value sym) (push sym symbols))) table)
> > +    (mapatoms (lambda (sym)
> > +                (if (and (symbol-value sym) (not (abbrev-get sym :system)))
>                                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
> Looks like the second check you added implements the "Abbrevs marked as
> \"system abbrevs\" are omitted" part.  I guess that actually fixes an
> additional bug?  Worth mentioning in the commit message, I think.

The system abbrev omitting worked (if readable is nil); it's
implemented in abbrev--write.
However, that doesn't allow us to skip writing a table if it only
contains system abbrevs;
we'll still see a table with abbrevs, write the opening of the
define-abbrev-table form,
and then realize in abbrev-write that all of the abbrevs are system abbrevs.

I noticed a bug in my patch where it would skip system abbrevs if
readable was non-nil
when it did not skip system abbrevs previously.  I fixed this and also
fixed the docstring
to match what I believe is the intended behavior.

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From 114b8ae71b8a87d4459c45bc8d571a534912a807 Mon Sep 17 00:00:00 2001
From: Allen Li <darkfeline@felesatra.moe>
Date: Sun, 31 Dec 2017 20:33:21 -0800
Subject: [PATCH] Skip writing empty abbrev tables

Fixes bug#29923

* lisp/abbrev.el (insert-abbrev-table-description):
Skip inserting empty tables when READABLE is non-nil.
Clarify behavior in documentation string.
---
 lisp/abbrev.el | 43 ++++++++++++++++++++++++-------------------
 1 file changed, 24 insertions(+), 19 deletions(-)

diff --git a/lisp/abbrev.el b/lisp/abbrev.el
index cddce8f529..ac01363357 100644
--- a/lisp/abbrev.el
+++ b/lisp/abbrev.el
@@ -938,27 +938,32 @@ insert-abbrev-table-description
 a call to `define-abbrev-table', which would
 define the abbrev table NAME exactly as it is currently defined.
 
-Abbrevs marked as \"system abbrevs\" are omitted."
+If READABLE is nil, abbrevs marked as \"system abbrevs\" and
+empty abbrev tables are omitted."
   (let ((table (symbol-value name))
         (symbols ()))
-    (mapatoms (lambda (sym) (if (symbol-value sym) (push sym symbols))) table)
-    (setq symbols (sort symbols 'string-lessp))
-    (let ((standard-output (current-buffer)))
-      (if readable
-	  (progn
-	    (insert "(")
-	    (prin1 name)
-	    (insert ")\n\n")
-	    (mapc 'abbrev--describe symbols)
-	    (insert "\n\n"))
-	(insert "(define-abbrev-table '")
-	(prin1 name)
-	(if (null symbols)
-	    (insert " '())\n\n")
-	  (insert "\n  '(\n")
-	  (mapc 'abbrev--write symbols)
-	  (insert "   ))\n\n")))
-      nil)))
+    (mapatoms (lambda (sym)
+                (if (and (symbol-value sym) (or readable (not (abbrev-get sym :system))))
+                    (push sym symbols)))
+              table)
+    (when symbols
+      (setq symbols (sort symbols 'string-lessp))
+      (let ((standard-output (current-buffer)))
+        (if readable
+            (progn
+              (insert "(")
+              (prin1 name)
+              (insert ")\n\n")
+              (mapc 'abbrev--describe symbols)
+              (insert "\n\n"))
+          (insert "(define-abbrev-table '")
+          (prin1 name)
+          (if (null symbols)
+              (insert " '())\n\n")
+            (insert "\n  '(\n")
+            (mapc 'abbrev--write symbols)
+            (insert "   ))\n\n")))
+        nil))))
 
 (defun define-abbrev-table (tablename definitions
                                       &optional docstring &rest props)
-- 
2.19.0.397.gdd90340f6a-goog