flet is obsolete, but...

flet is obsolete, but...

[Sebastien Vauban]

Hello,

`flet' is an obsolete macro (as of 24.3); use either `cl-flet' or `cl-letf'.

But doing so in the following code:

--8<---------------cut here---------------start------------->8---
  (defun my/revert-buffer ()
    "Unconditionally revert current buffer."
    (interactive)
    (flet ((yes-or-no-p (msg) t))
      (revert-buffer)))
--8<---------------cut here---------------end--------------->8---

does not lead to the right things:

- use cl-flet, and the code doesn't behave as it should (i.e., it does ask for
  a confirmation, before reverting)

- use cl-letf, and you've got an error:
  cl-letf: `let' bindings can have only one value-form: yes-or-no-p, (msg), t

What should I do?

Best regards,
  Seb

-- 
Sebastien Vauban

Re: flet is obsolete, but...

[Jambunathan K]

> Hello,
>
> `flet' is an obsolete macro (as of 24.3); use either `cl-flet' or `cl-letf'.
>
> But doing so in the following code:
>
>
>   (defun my/revert-buffer ()
>     "Unconditionally revert current buffer."
>     (interactive)
>     (flet ((yes-or-no-p (msg) t))
>       (revert-buffer)))
>
>
> does not lead to the right things:
>
> - use cl-flet, and the code doesn't behave as it should (i.e., it does ask for
>   a confirmation, before reverting)
>
> - use cl-letf, and you've got an error:
>   cl-letf: `let' bindings can have only one value-form: yes-or-no-p, (msg), t
>
> What should I do?

Use the NOCONFIRM of revert-buffer.

> Best regards,
>   Seb

-- 

Re: flet is obsolete, but...

[Jambunathan K]

> Hello,
>
> `flet' is an obsolete macro (as of 24.3); use either `cl-flet' or `cl-letf'.
>
> But doing so in the following code:
>
>
>   (defun my/revert-buffer ()
>     "Unconditionally revert current buffer."
>     (interactive)
>     (flet ((yes-or-no-p (msg) t))
>       (revert-buffer)))
>
>
> does not lead to the right things:
>
> - use cl-flet, and the code doesn't behave as it should (i.e., it does ask for
>   a confirmation, before reverting)
>
> - use cl-letf, and you've got an error:
>   cl-letf: `let' bindings can have only one value-form: yes-or-no-p, (msg), t
>
> What should I do?

Use the NOCONFIRM argument of revert-buffer.

> Best regards,
>   Seb

-- 

Re: flet is obsolete, but...

[Barry Margolin]

In article <804nm2zekk.fsf@somewhere.org>,
 "Sebastien Vauban" <wxhgmqzgwmuf@spammotel.com> wrote:

> Hello,
> 
> `flet' is an obsolete macro (as of 24.3); use either `cl-flet' or `cl-letf'.
> 
> But doing so in the following code:
> 
> --8<---------------cut here---------------start------------->8---
>   (defun my/revert-buffer ()
>     "Unconditionally revert current buffer."
>     (interactive)
>     (flet ((yes-or-no-p (msg) t))
>       (revert-buffer)))
> --8<---------------cut here---------------end--------------->8---
> 
> does not lead to the right things:
> 
> - use cl-flet, and the code doesn't behave as it should (i.e., it does ask for
>   a confirmation, before reverting)'

cl-flet does lexical binding, not dynamic.

> 
> - use cl-letf, and you've got an error:
>   cl-letf: `let' bindings can have only one value-form: yes-or-no-p, (msg), t
> 
> What should I do?

Sounds like you didn't write your cl-letf correctly. Did you read its 
documentation? It's not a drop-in replacement for flet, since it's more 
general than this (it's used to temporarily assign to any place that can 
be set with setf).

(letf (((symbol-function 'yes-or-no-p)
           #'(lambda (msg) t)))
  (revert-buffer))

-- 
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***

Re: flet is obsolete, but...

[Sebastien Vauban]

Hi Jambunathan,

Jambunathan K wrote:
>> `flet' is an obsolete macro (as of 24.3); use either `cl-flet' or `cl-letf'.
>>
>> But doing so in the following code:
>>
>>   (defun my/revert-buffer ()
>>     "Unconditionally revert current buffer."
>>     (interactive)
>>     (flet ((yes-or-no-p (msg) t))
>>       (revert-buffer)))
>>
>> does not lead to the right things:
>> What should I do?
>
> Use the NOCONFIRM argument of revert-buffer.

I tried another way:

--8<---------------cut here---------------start------------->8---
  (defun my/revert-buffer ()
    "Unconditionally revert current buffer."
    (interactive)
    (let ((revert-without-query t))
      (revert-buffer)))
--8<---------------cut here---------------end--------------->8---

but I don't understand why it does not work:

--8<---------------cut here---------------start------------->8---
Debugger entered--Lisp error: (wrong-type-argument listp t)
  byte-code("\b\304\211\205\x1f\n@\305	\v\"\203

Re: flet is obsolete, but...

[Tassilo Horn]

"Sebastien Vauban"
<wxhgmqzgwmuf@spammotel.com> writes:

>> Use the NOCONFIRM argument of revert-buffer.
>
> I tried another way:

What's wrong with NOCONFIRM?

>   (defun my/revert-buffer ()
>     "Unconditionally revert current buffer."
>     (interactive)
>     (let ((revert-without-query t))
>       (revert-buffer)))
>
> but I don't understand why it does not work:
>
> --8<---------------cut here---------------start------------->8---
> Debugger entered--Lisp error: (wrong-type-argument listp t)
>   byte-code("\b\304\211\205\x1f\n@\305	\v\"\203

Because t is not a list.  The docs clearly state that
`revert-without-query' has to be a list of regular expressions.

,----[ C-h v revert-without-query RET ]
| revert-without-query is a variable defined in `files.el'.
| Its value is nil
| 
| Documentation:
| Specify which files should be reverted without query.
| The value is a list of regular expressions.
| If the file name matches one of these regular expressions,
| then `revert-buffer' reverts the file without querying
| if the file has changed on disk and you have not edited the buffer.
`----

Bye,
Tassilo

Re: flet is obsolete, but...

[Jambunathan K]

"Sebastien Vauban"
<wxhgmqzgwmuf-geNee64TY+gS+FvcfC7Uqw@public.gmane.org> writes:

> Hi Jambunathan,
>
> Jambunathan K wrote:
>>> `flet' is an obsolete macro (as of 24.3); use either `cl-flet' or `cl-letf'.
>>>
>>> But doing so in the following code:
>>>
>>>   (defun my/revert-buffer ()
>>>     "Unconditionally revert current buffer."
>>>     (interactive)
>>>     (flet ((yes-or-no-p (msg) t))
>>>       (revert-buffer)))
>>>
>>> does not lead to the right things:
>>> What should I do?
>>
>> Use the NOCONFIRM argument of revert-buffer.
>
> I tried another way:
>
>
>   (defun my/revert-buffer ()
>     "Unconditionally revert current buffer."
>     (interactive)
>     (let ((revert-without-query t))
>       (revert-buffer)))
>
>
> but I don't understand why it does not work:
>
> --8<---------------cut here---------------start------------->8---
> Debugger entered--Lisp error: (wrong-type-argument listp t)
>   byte-code("\b\304\211\205\x1f\n@\305	\v\"\203
>

listp in above Lisp error gives a clue that a list is expected.

A describe variable confirms that it is indeed a list regexes.  Regex is
a Emacs regex and NOT a shell-regex.

,----[ C-h v revert-without-query RET ]
| revert-without-query is a variable defined in `files.el'.
| Its value is nil
| 
| Documentation:
| Specify which files should be reverted without query.
| The value is a list of regular expressions.
| If the file name matches one of these regular expressions,
| then `revert-buffer' reverts the file without querying
| if the file has changed on disk and you have not edited the buffer.
| 
| You can customize this variable.
| 
| [back]
`----


-- 

RE: flet is obsolete, but...

[Drew Adams]

>   (defun my/revert-buffer ()
>     "Unconditionally revert current buffer."
>     (interactive)
>     (let ((revert-without-query t)) (revert-buffer)))
> 
> but I don't understand why it does not work:

Others have explained why it does not work.
Here's another way:

(defun revert-buffer-no-confirm ()
  "Revert buffer without confirmation."
  (interactive) (revert-buffer t t))

(I bind it to `f5', in keeping with the MS Windows use of that key.)

RE: flet is obsolete, but...

[Ludwig, Mark]

> -----Original Message-----
> From: Drew Adams
> Sent: Thursday, October 11, 2012 8:49 AM
> To: 'Sebastien Vauban'; help-gnu-emacs@gnu.org
> Subject: RE: flet is obsolete, but...
> 
> (I bind [revert-buffer-no-confirm] to `f5', in keeping with the MS Windows use of that key.)

That's the best idea I've seen in a /long/ time.  Why didn't /I/ think of that?!  

Thanks!
Mark

Re: flet is obsolete, but...

[Sebastien Vauban]

Hello all,

Barry Margolin wrote:
> In article <804nm2zekk.fsf-oHC15RC7JGTNLxjTenLetw@public.gmane.org>,
>  "Sebastien Vauban" <wxhgmqzgwmuf-geNee64TY+gS+FvcfC7Uqw@public.gmane.org> wrote:
>
>> Hello,
>> 
>> `flet' is an obsolete macro (as of 24.3); use either `cl-flet' or `cl-letf'.
>> 
>> But doing so in the following code:
>> 
>> --8<---------------cut here---------------start------------->8---
>>   (defun my/revert-buffer ()
>>     "Unconditionally revert current buffer."
>>     (interactive)
>>     (flet ((yes-or-no-p (msg) t))
>>       (revert-buffer)))
>> --8<---------------cut here---------------end--------------->8---
>> 
>> does not lead to the right things:
>> 
>> - use cl-flet, and the code doesn't behave as it should (i.e., it does ask for
>>   a confirmation, before reverting)'
>
> cl-flet does lexical binding, not dynamic.
>
>> 
>> - use cl-letf, and you've got an error:
>>   cl-letf: `let' bindings can have only one value-form: yes-or-no-p, (msg), t
>> 
>> What should I do?
>
> Sounds like you didn't write your cl-letf correctly. Did you read its 
> documentation? It's not a drop-in replacement for flet, since it's more 
> general than this (it's used to temporarily assign to any place that can 
> be set with setf).
>
> (letf (((symbol-function 'yes-or-no-p)
>            #'(lambda (msg) t)))
>   (revert-buffer))

Thanks for your answers. It helped a lot, even if the above is still a bit
cryptic to me.

And, yes, I thought that the replacement was purely a syntaxical exchange of
words...

Best regards,
  Seb

-- 
Sebastien Vauban

`f5' for refreshing/reverting without confirmation [was: flet is obsolete, but...]

[Drew Adams]

> > (I bind [revert-buffer-no-confirm] to `f5', in keeping with 
> > the MS Windows use of that key.)
> 
> That's the best idea I've seen in a /long/ time.
> Why didn't /I/ think of that?!  

You're welcome.  Sometimes a trivial change can make a difference.

I must say that "wasting" an easy, repeatable key such as `f5' on this (as
opposed to binding it to a command that could take advantage of holding down the
key to repeat) goes against my general guidelines.

But in this case I made an exception because I already have the habit of using
it in Windows apps, so it is handy (for me).