with-wrapper-hook is obsolete; how to replace it?

with-wrapper-hook is obsolete; how to replace it?

[Paul Eggert]

When I run ‘make compile-always’ from the lisp subdirectory I see diagnostics
like this:

In buffer-substring--filter:
simple.el:4058:52:Warning: ‘with-wrapper-hook’ is an obsolete macro (as of
    24.4); use a <foo>-function variable modified by ‘add-function’.

How do I alter the code to use add-function instead? It's not immediately
obvious. That is, if there is source code like this:

    (with-wrapper-hook filter-buffer-substring-functions (beg end delete) BODY)

where filter-buffer-substring-functions is defined like this:

  (defvar filter-buffer-substring-functions nil
    "This variable is a wrapper hook around `buffer-substring--filter'.")

then what should I replace the source code with?

Re: with-wrapper-hook is obsolete; how to replace it?

[Stefan Monnier]

> How do I alter the code to use add-function instead?
> It's not immediately obvious. That is, if there is source code like this:

I don't think you can do it in a backward-compatible way.
Which is why buffer-substring--filter still uses with-wrapper-hook (but
only to implement the obsolete filter-buffer-substring-functions variable).

> then what should I replace the source code with?

The replacement is that instead of using add-hook on
filter-buffer-substring-functions, clients should now use add-function
on filter-buffer-substring-function.


        Stefan

Re: with-wrapper-hook is obsolete; how to replace it?

[Paul Eggert]

[-- Attachment #1: Type: text/plain, Size: 504 bytes --]

On 05/15/2016 11:43 AM, Stefan Monnier wrote:
> I don't think you can do it in a backward-compatible way.
> Which is why buffer-substring--filter still uses with-wrapper-hook (but
> only to implement the obsolete filter-buffer-substring-functions variable).

OK, thanks, how about the attached patch instead? The idea is to pacify 
the byte compiler without attempting to use add-function, by creating an 
internal-use-only version of the obsolete macro, a version that does not 
generate the warnings.


[-- Attachment #2: with-wrapper-hook.diff --]
[-- Type: text/x-patch, Size: 2480 bytes --]

diff --git a/lisp/abbrev.el b/lisp/abbrev.el
index 7814ea2..163dc8e 100644
--- a/lisp/abbrev.el
+++ b/lisp/abbrev.el
@@ -848,7 +848,7 @@ abbrev--default-expand
   "Default function to use for `abbrev-expand-function'.
 This respects the wrapper hook `abbrev-expand-functions'.
 Calls `abbrev-insert' to insert any expansion, and returns what it does."
-  (with-wrapper-hook abbrev-expand-functions ()
+  (subr--with-wrapper-hook-no-warnings abbrev-expand-functions ()
     (pcase-let ((`(,sym ,name ,wordstart ,wordend) (abbrev--before-point)))
       (when sym
         (let ((startpos (copy-marker (point) t))
diff --git a/lisp/minibuffer.el b/lisp/minibuffer.el
index 1ee05d3..9190c1f 100644
--- a/lisp/minibuffer.el
+++ b/lisp/minibuffer.el
@@ -1970,7 +1970,7 @@ completion--in-region
   "Default function to use for `completion-in-region-function'.
 Its arguments and return value are as specified for `completion-in-region'.
 This respects the wrapper hook `completion-in-region-functions'."
-  (with-wrapper-hook
+  (subr--with-wrapper-hook-no-warnings
       ;; FIXME: Maybe we should use this hook to provide a "display
       ;; completions" operation as well.
       completion-in-region-functions (start end collection predicate)
diff --git a/lisp/simple.el b/lisp/simple.el
index e257062..65664c9 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -4061,7 +4061,8 @@ buffer-substring--filter
 This respects the wrapper hook `filter-buffer-substring-functions',
 and the abnormal hook `buffer-substring-filters'.
 No filtering is done unless a hook says to."
-  (with-wrapper-hook filter-buffer-substring-functions (beg end delete)
+  (subr--with-wrapper-hook-no-warnings
+    filter-buffer-substring-functions (beg end delete)
     (cond
      ((or delete buffer-substring-filters)
       (save-excursion
diff --git a/lisp/subr.el b/lisp/subr.el
index 0fa6404..438f00a 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -1546,6 +1546,10 @@ with-wrapper-hook
   (declare (indent 2) (debug (form sexp body))
            (obsolete "use a <foo>-function variable modified by `add-function'."
                      "24.4"))
+  `(subr--with-wrapper-hook-no-warnings ,hook ,args ,@body))
+
+(defmacro subr--with-wrapper-hook-no-warnings (hook args &rest body)
+  "Like (with-wrapper-hook HOOK ARGS BODY), but without warnings."
   ;; We need those two gensyms because CL's lexical scoping is not available
   ;; for function arguments :-(
   (let ((funs (make-symbol "funs"))

Re: with-wrapper-hook is obsolete; how to replace it?

[Stefan Monnier]

> OK, thanks, how about the attached patch instead?

Fine by me,


        Stefan

Re: with-wrapper-hook is obsolete; how to replace it?

[Stefan Monnier]

[ Hmm... I can't seem to see my reply, so I'll send it again.  ]

> When I run ‘make compile-always’ from the lisp subdirectory I see diagnostics
> like this:

> In buffer-substring--filter:
> simple.el:4058:52:Warning: ‘with-wrapper-hook’ is an obsolete macro (as of
>     24.4); use a <foo>-function variable modified by ‘add-function’.

> How do I alter the code to use add-function instead?

Here's a translation table:

  +---------------------+-----------------+----------------+
  |  with-wrapper-hook  |  foo-functions  |  add-hook      |
  +---------------------+-----------------+----------------+
  |  funcall            |  foo-function   |  add-function  |
  +---------------------+-----------------+----------------+

This replacement has already been done in buffer-substring, but we still
need to use the obsolete with-wrapper-hook in order to support the
corresponding obsolete filter-buffer-substring-functions variable.


        Stefan