How to avoid warning, with undefined functions in a package

How to avoid warning, with undefined functions in a package

[Jean Louis]

Let us say I have some speech functions, but do not want to
(require 'festival) for the package rcd-utilities.el

Those are undefined functions and variables, but I would not like
defining them, or requiring them, unless user has that other package.

What would be good approach to solve that, and that there are no
compiler warnings?

In rcd-speak-festival:
rcd-utilities.el:121:23: Warning: reference to free variable
    ‘festival-program-name’

In end of data:
rcd-utilities.el:205:1: Warning: the function ‘festival-say-string’ is not
    known to be defined.

Re: How to avoid warning, with undefined functions in a package

[Daniel Martín]

Jean Louis <bugs@gnu.support> writes:

> Let us say I have some speech functions, but do not want to
> (require 'festival) for the package rcd-utilities.el
>
> Those are undefined functions and variables, but I would not like
> defining them, or requiring them, unless user has that other package.
>
> What would be good approach to solve that, and that there are no
> compiler warnings?
>
> In rcd-speak-festival:
> rcd-utilities.el:121:23: Warning: reference to free variable
>     ‘festival-program-name’
>
> In end of data:
> rcd-utilities.el:205:1: Warning: the function ‘festival-say-string’ is not
>     known to be defined.

There are several possible techniques. The Elisp manual explains some of
them:

C-h i m Elisp RET i byte-compiler warnings RET

RE: How to avoid warning, with undefined functions in a package

[Drew Adams]

> Those are undefined functions and variables, but I would not like
> defining them, or requiring them, unless user has that other package.
> 
> What would be good approach to solve that, and that there are no
> compiler warnings?
> 
> In rcd-speak-festival:
> rcd-utilities.el:121:23: Warning: reference to free variable
>     ‘festival-program-name’

For the undefined variable warnings: If you are convinced that your code does the right thing, so those warnings are spurious, add an empty `defvar' for each such variable warning.  E.g., for variable foo, add this:

;; No initial value.  Just tells the byte compiler
;; that this is a special variable.
;;
(defvar foo)

Re: How to avoid warning, with undefined functions in a package

[Jean Louis]

* Drew Adams <drew.adams@oracle.com> [2020-10-19 18:17]:
> > Those are undefined functions and variables, but I would not like
> > defining them, or requiring them, unless user has that other package.
> > 
> > What would be good approach to solve that, and that there are no
> > compiler warnings?
> > 
> > In rcd-speak-festival:
> > rcd-utilities.el:121:23: Warning: reference to free variable
> >     ‘festival-program-name’
> 
> For the undefined variable warnings: If you are convinced that your code does the right thing, so those warnings are spurious, add an empty `defvar' for each such variable warning.  E.g., for variable foo, add this:
> 
> ;; No initial value.  Just tells the byte compiler
> ;; that this is a special variable.
> ;;
> (defvar foo)

Thank you, that is also good to know.

What I did is that I made like:

(defvar rcd-festival-function 'festival-say-string "Which festival function to be called")
(setq rcd-speech-function 'rcd-speak-festival)

and I use bound-and-true-p to avoid the warning down.

(defun rcd-speak-festival (string)
  "Returns speech by using festival if the `rcd-speech' variables
is true and `festival-program-name' has some value"
  (if (and rcd-speech (bound-and-true-p festival-program-name))
      (funcall rcd-festival-function string)))

In case there are different festival functions, it is
configurable. That is my idea of it. Now there are no warning.

Re: How to avoid warning, with undefined functions in a package

[Emanuel Berg via Users list for the GNU Emacs text editor]

Jean Louis wrote:

> Thank you, that is also good to know.
>
> What I did is that I made like:
>
> (defvar rcd-festival-function 'festival-say-string
> "Which festival function to be called") (setq
> rcd-speech-function 'rcd-speak-festival)
>
> and I use bound-and-true-p to avoid the
> warning down.

Well ... OK :)

Another way is to put it in an lsd-festival elisp
_file_, which has a `provide' line last.

Then use `require' topmost in the elisp files where
it is used...

As for vars, yes, use `defvar'

Then byte-compile everything (seemingly) at once
using a Makefile.

Examples:
  
  https://dataswamp.org/~incal/emacs-init/isbn-verify.el
  https://dataswamp.org/~incal/emacs-init/issn-verify.el
  https://dataswamp.org/~incal/emacs-init/Makefile
  
-- 
underground experts united
http://user.it.uu.se/~embe8573
https://dataswamp.org/~incal