goof in small function where???

goof in small function where???

[ken]

The function below half works: it does put the buffer-file-name into the 
kill ring, but nothing is displayed in the minibuffer.  Why?  And how to 
fix this?

(defun file-name-into-kill-buffer ()
"Put path/filename of current buffer onto kill-ring so to paste
into an X application.  Also display it in minibuffer."
(interactive)
      (let ((str (buffer-file-name)))
        (and str
             (kill-new str)
             (message "Copied filename %s to kill ring" str)))
)

Thanks much.

Re: goof in small function where???

[Michael Heerdegen]

ken <gebser@mousecar.com> writes:

> (defun file-name-into-kill-buffer ()
> "Put path/filename of current buffer onto kill-ring so to paste
> into an X application.  Also display it in minibuffer."
> (interactive)
>      (let ((str (buffer-file-name)))
>        (and str
>             (kill-new str)
>             (message "Copied filename %s to kill ring" str)))
> )

This doesn't work when `kill-new' returns nil, which happens when
`interprogram-cut-function' is nil (which is the default).  Note that
the doc of `kill-new' doesn't say anything about the return value, it
can be anything.

Ergo: the `and' should better be a `when'.

Re: goof in small function where???

[ken]

On 07/22/2014 06:02 AM Michael Heerdegen wrote:
> ken <gebser@mousecar.com> writes:
>
>> (defun file-name-into-kill-buffer ()
>> "Put path/filename of current buffer onto kill-ring so to paste
>> into an X application.  Also display it in minibuffer."
>> (interactive)
>>       (let ((str (buffer-file-name)))
>>         (and str
>>              (kill-new str)
>>              (message "Copied filename %s to kill ring" str)))
>> )
>
> This doesn't work when `kill-new' returns nil, which happens when
> `interprogram-cut-function' is nil (which is the default).  Note that
> the doc of `kill-new' doesn't say anything about the return value, it
> can be anything.
>
> Ergo: the `and' should better be a `when'.

Yes!  That fixed it!!  Thanks very much.

I'm vaguely understanding that the 'and' doesn't evaluate '(message...' 
when '(kill-new...' returns nil and, since its return value is 
undefined, it can do on occasion.  Replacing 'and' with 'when' ensures 
'(message...' is evaluated regardless of what '(kill-new...' returns.

Is that about right?


Thanks again.

Re: goof in small function where???

[Michael Heerdegen]

ken <gebser@mousecar.com> writes:

> I'm vaguely understanding that the 'and' doesn't evaluate
> '(message...' when '(kill-new...' returns nil and, since its return
> value is undefined, it can do on occasion.  Replacing 'and' with
> 'when' ensures '(message...' is evaluated regardless of what
> '(kill-new...' returns.
>
> Is that about right?

Exactly.  `and' is not the right way to tell Emacs "do this _and_
that" ;-) 

The following would also be ok, btw:

         (and str
              (progn (kill-new str)
                     (message "Copied filename %s to kill ring" str)))

Regards,

Michael.

Re: goof in small function where???

[Thorsten Jolitz]

ken <gebser@mousecar.com> writes:

> The function below half works: it does put the buffer-file-name into
> the kill ring, but nothing is displayed in the minibuffer.  Why?  And
> how to fix this?
>
> (defun file-name-into-kill-buffer ()
> "Put path/filename of current buffer onto kill-ring so to paste
> into an X application.  Also display it in minibuffer."
> (interactive)
>      (let ((str (buffer-file-name)))
>        (and str
>             (kill-new str)
>             (message "Copied filename %s to kill ring" str)))
> )

Try:

#+begin_src emacs-lisp
  (defun tj/file-name-into-kill-buffer ()
    "Put path/filename of current buffer onto kill-ring so to paste
  into an X application.  Also display it in minibuffer."
    (interactive)
    (let ((str (buffer-file-name)))
      (when str
        (kill-new str)
        (message "Copied filename %s to kill ring" str))))
#+end_src

#+results:
: tj/file-name-into-kill-buffer

#+begin_src emacs-lisp
 (tj/file-name-into-kill-buffer)
#+end_src

#+results:
: Copied filename /home/tj/News/drafts/drafts/853 to kill ring

I guess `kill-new` is for side-effects only and returns nil, so in your
version the `message` call is never executed.

-- 
cheers,
Thorsten

Re: goof in small function where???

[Thorsten Jolitz]

Thorsten Jolitz <tjolitz@gmail.com> writes:

> ken <gebser@mousecar.com> writes:
>
>> The function below half works: it does put the buffer-file-name into
>> the kill ring, but nothing is displayed in the minibuffer.  Why?  And
>> how to fix this?

> Try: ...

ok, I should have pressed 'g' in gnus first before answering - too late
to the party ;)

-- 
cheers,
Thorsten

Re: goof in small function where???

[Michael Heerdegen]

Thorsten Jolitz <tjolitz@gmail.com> writes:

> ok, I should have pressed 'g' in gnus first before answering - too late
> to the party ;)

I'm happy that this time I'm not the one who is saying that :-P

Re: goof in small function where???

[Joost Kremers]

ken wrote:
> The function below half works: it does put the buffer-file-name into the 
> kill ring, but nothing is displayed in the minibuffer.  Why?  And how to 
> fix this?
>
> (defun file-name-into-kill-buffer ()
> "Put path/filename of current buffer onto kill-ring so to paste
> into an X application.  Also display it in minibuffer."
> (interactive)
>       (let ((str (buffer-file-name)))
>         (and str
>              (kill-new str)
>              (message "Copied filename %s to kill ring" str)))
> )

Works for me. You're probably doing something (or Emacs does something)
that makes the message disappear right away. (Messages in the minibuffer
disappear as soon as you press a key or even hit a cursor key.)

Check the *Messages* buffer if the message is there (`C-h e` or mouse-1
in the minibuffer.[1])

HTH

Joost


[1] Thanks, Drew. (Sincerely.)

-- 
Joost Kremers                                   joostkremers@fastmail.fm
Selbst in die Unterwelt dringt durch Spalten Licht
EN:SiS(9)

Re: goof in small function where???

[ken]

On 07/22/2014 05:41 AM Joost Kremers wrote:
> ken wrote:
>> The function below half works: it does put the buffer-file-name into the
>> kill ring, but nothing is displayed in the minibuffer.  Why?  And how to
>> fix this?
>>
>> (defun file-name-into-kill-buffer ()
>> "Put path/filename of current buffer onto kill-ring so to paste
>> into an X application.  Also display it in minibuffer."
>> (interactive)
>>        (let ((str (buffer-file-name)))
>>          (and str
>>               (kill-new str)
>>               (message "Copied filename %s to kill ring" str)))
>> )
>
> Works for me. You're probably doing something (or Emacs does something)
> that makes the message disappear right away. (Messages in the minibuffer
> disappear as soon as you press a key or even hit a cursor key.)
>
> Check the *Messages* buffer if the message is there (`C-h e` or mouse-1
> in the minibuffer.[1])
>
> HTH
>
> Joost

Thanks, Joost.  But "Copied filename..." isn't anywhere in *Messages* 
buffer.  If, however, I do in a file:

(message "Hello Message")C-x C-e

I do see "Hello Message" in the minibuffer and (some seconds later) in 
*Messages*.

Very weird!  How could this be?