[Warning] cl-count (And Other Options)

[Warning] cl-count (And Other Options)

[Eric James Michael Ritz]

First my apologies if this email would be more appropriate elsewhere.

I am currently using GNU Emacs 24.2.90.1 (i686-pc-linux-gnu, GTK+
Version 2.24.13), compiled on the 24th of November 2012.  In a
function in my php-mode [1] I have the following function definition:

     (defun php-unindent-closure ()
       (let ((syntax (mapcar 'car c-syntactic-context)))
         (if (and (member 'arglist-cont-nonempty syntax)
                  (or
                   (member 'statement-block-intro syntax)
                   (member 'brace-list-intro syntax)
                   (member 'brace-list-close syntax)
                   (member 'block-close syntax)))
             (save-excursion
               (let ((count-func (if (fboundp 'cl-count) #'cl-count 
#'count)())))
               (beginning-of-line)
               (delete-char (* (cl-count 'arglist-cont-nonempty syntax)
                               c-basic-offset))))))

The key thing to note (unless you see something glaringly wrong with
it) is the call to `cl-count`.  When I compile the file containing the
function I receive the following warning:

     Compiling file /home/eric/Projects/php-mode/php-mode.el at Fri Nov 
30 16:49:05 2012

     In php-unindent-closure:
     php-mode.el:436:8:Warning: malformed let binding: `(count-func (if 
(fboundp
         (quote cl-count)) (function cl-count) (function count)) nil)

The warning leads me to believe that use of `cl-count` is not
encouraged.  Is that the case?  And if so, what would be my best
alternative which would not trigger a warning?

Thank you in advanced!

[1]: https://github.com/ejmr/php-mode

--
ejmr
南無妙法蓮華經

Re: [Warning] cl-count (And Other Options)

[Dmitry Gutov]

Eric James Michael Ritz <lobbyjones@gmail.com> writes:

> First my apologies if this email would be more appropriate elsewhere.
>
> I am currently using GNU Emacs 24.2.90.1 (i686-pc-linux-gnu, GTK+
> Version 2.24.13), compiled on the 24th of November 2012.  In a
> function in my php-mode [1] I have the following function definition:
>
>     (defun php-unindent-closure ()
>       (let ((syntax (mapcar 'car c-syntactic-context)))
>         (if (and (member 'arglist-cont-nonempty syntax)
>                  (or
>                   (member 'statement-block-intro syntax)
>                   (member 'brace-list-intro syntax)
>                   (member 'brace-list-close syntax)
>                   (member 'block-close syntax)))
>             (save-excursion
>               (let ((count-func (if (fboundp 'cl-count) #'cl-count #'count)())))
>               (beginning-of-line)
>               (delete-char (* (cl-count 'arglist-cont-nonempty syntax)
>                               c-basic-offset))))))
>
> The key thing to note (unless you see something glaringly wrong with
> it) is the call to `cl-count`.  When I compile the file containing the
> function I receive the following warning:
>
>     Compiling file /home/eric/Projects/php-mode/php-mode.el at Fri Nov 30
> 16:49:05 2012
>
>     In php-unindent-closure:
>     php-mode.el:436:8:Warning: malformed let binding: `(count-func (if (fboundp
>         (quote cl-count)) (function cl-count) (function count)) nil)
>
> The warning leads me to believe that use of `cl-count` is not
> encouraged.  Is that the case?  And if so, what would be my best
> alternative which would not trigger a warning?

The warning tries to tell you that you have a spurious "()" in the let
binding form, after the value you are assigning to count-func.

It doesn't mention the actual problems:
1) The let form's body is empty, while it should contain the code that
goes after it.
2) Replace that (cl-count ...) with (funcall count-func ...).

But what Drew meant, I think, if for you the create a prefixed function
alias, not local value binding. The former would just look better in
code.

RE: [Warning] cl-count (And Other Options)

[Drew Adams]

> > (let ((count-func (if (fboundp 'cl-count) #'cl-count #'count)())))
> >   ...
> >   (delete-char (* (cl-count ...)...
> >
> > php-mode.el:436:8:Warning: malformed let binding: 
>
> The warning tries to tell you that ...

the let binding is malformed. ;-)

> 2) Replace that (cl-count ...) with (funcall count-func ...).

Yes.  Calling `cl-count' just, well, calls `cl-count'. ;-)

The point was to call `cl-count' if it exists, or call `count' if not.  `count'
is defined if `cl-count' is not defined.  Older Emacs uses the name `count';
newer Emacs uses the name `cl-count'.

> But what Drew meant, I think, if for you the create a prefixed
> function alias, not local value binding. The former would just
> look better in code.

That's OK too.

But all I really meant was to call the function that exists, whether it is named
`cl-count' or `count'.  One or the other is available, and they presumably do
the same thing.

Look first for a function with the newer name, `cl-count'.  If that does not
exist then use `count', which must exist prior to the introduction of
`cl-count'.

If you have only one or a few occurrences of `cl-count' in your code, you could
just replace them with a funcall of the right function, as indicated above.  If
you have a lot of them, or if you prefer (e.g. to ease maintenance), you can
create your own (non-local) function that calls the right one, and then use that
everywhere in your code.

(defun my-count (&rest args)
  (if (fboundp 'cl-count)
      (apply #'cl-count args)
    (apply #'count args)))

Or just:

(defalias 'my-count (if (fboundp 'cl-count) #'cl-count #'count))

Then (delete-char (* (my-count ...)... etc.