Using button-label in pcase

Using button-label in pcase

[uzibalqa]

Want to print some text as a result of clicking a button.  With the code below
I end up with

(wrong-type-argument integer-or-marker-p nil)
  buffer-substring-no-properties(nil nil)
  button-label(#<overlay in no buffer>)
  (let* ((val (button-label button))) (if (equal val '"[FA]") (let nil (insert qrh-c))))
  (closure ((button . #<overlay in no buffer>)) nil (let* ((val (button-label button))) (if (equal val '"[FA]") (let nil (insert qrh-c)))))()
  help--window-setup("*Help*" (closure ((button . #<overlay in no buffer>)) nil (let* ((val (button-label button))) (if (equal val '"[FA]") (let nil (insert qrh-c))))))
  qrh-b(#<overlay in no buffer>)
  button-activate(#<overlay in no buffer> t)
  push-button(3 t)

What is going on.  Is there a fix?

(defconst qrh-c "[FA] Some Text")

(defun qrh-b (button)
  "Prints information about how to install emacs."
  (with-help-window (help-buffer)
    (pcase (button-label button)
      ("[FA]" (insert qrh-c))) ))

(defun qrh-a ()
  "Prints information about how to install emacs."
  (interactive)
  (with-help-window (help-buffer)
    (insert-button "[FC]"
      'action 'qrh-b 'follow-link t) ))

Re: Using button-label in pcase

[Stephen Berman]

On Mon, 24 Jul 2023 19:14:27 +0000 uzibalqa <uzibalqa@proton.me> wrote:

> Want to print some text as a result of clicking a button.  With the code below
> I end up with
>
> (wrong-type-argument integer-or-marker-p nil)
>   buffer-substring-no-properties(nil nil)
>   button-label(#<overlay in no buffer>)
>   (let* ((val (button-label button))) (if (equal val '"[FA]") (let nil (insert qrh-c))))
>   (closure ((button . #<overlay in no buffer>)) nil (let* ((val (button-label button))) (if (equal val '"[FA]") (let nil (insert qrh-c)))))()
>   help--window-setup("*Help*" (closure ((button . #<overlay in no buffer>)) nil (let* ((val (button-label button))) (if (equal val '"[FA]") (let nil (insert qrh-c))))))
>   qrh-b(#<overlay in no buffer>)
>   button-activate(#<overlay in no buffer> t)
>   push-button(3 t)
>
> What is going on.  Is there a fix?
>
> (defconst qrh-c "[FA] Some Text")
>
> (defun qrh-b (button)
>   "Prints information about how to install emacs."
>   (with-help-window (help-buffer)
>     (pcase (button-label button)
>       ("[FA]" (insert qrh-c))) ))
>
> (defun qrh-a ()
>   "Prints information about how to install emacs."
>   (interactive)
>   (with-help-window (help-buffer)
>     (insert-button "[FC]"
>       'action 'qrh-b 'follow-link t) ))

The error is raised because qrh-b calls with-help-window with the *Help*
buffer current, but with-help-window erases the buffer, so when
`(button-label button)' is evaluated, there is no button and this
signals the error.

If you want to use the existing *Help* buffer, just remove the call to
with-help-window in qrh-b.  However, *Help* buffers are read-only, so
trying to insert text will raise another error.  To avoid this, you can
let-bind buffer-read-only in qrh-b.  However, since qrh-a inserts "[FC]"
but qrh-b tries to match "[FA]", the match will fail, so the insertion
in qrh-b will not happen.

Steve Berman

Re: Using button-label in pcase

[uzibalqa]

------- Original Message -------
On Tuesday, July 25th, 2023 at 8:07 AM, Stephen Berman <stephen.berman@gmx.net> wrote:


> On Mon, 24 Jul 2023 19:14:27 +0000 uzibalqa uzibalqa@proton.me wrote:
> 
> > Want to print some text as a result of clicking a button. With the code below
> > I end up with
> > 
> > (wrong-type-argument integer-or-marker-p nil)
> > buffer-substring-no-properties(nil nil)
> > button-label(#<overlay in no buffer>)
> > (let* ((val (button-label button))) (if (equal val '"[FA]") (let nil (insert qrh-c))))
> > (closure ((button . #<overlay in no buffer>)) nil (let* ((val (button-label button))) (if (equal val '"[FA]") (let nil (insert qrh-c)))))()
> > help--window-setup("Help" (closure ((button . #<overlay in no buffer>)) nil (let* ((val (button-label button))) (if (equal val '"[FA]") (let nil (insert qrh-c))))))
> > qrh-b(#<overlay in no buffer>)
> > button-activate(#<overlay in no buffer> t)
> > push-button(3 t)
> > 
> > What is going on. Is there a fix?
> > 
> > (defconst qrh-c "[FA] Some Text")
> > 
> > (defun qrh-b (button)
> > "Prints information about how to install emacs."
> > (with-help-window (help-buffer)
> > (pcase (button-label button)
> > ("[FA]" (insert qrh-c))) ))
> > 
> > (defun qrh-a ()
> > "Prints information about how to install emacs."
> > (interactive)
> > (with-help-window (help-buffer)
> > (insert-button "[FC]"
> > 'action 'qrh-b 'follow-link t) ))
> 
> The error is raised because qrh-b calls with-help-window with the Help
> buffer current, but with-help-window erases the buffer, so when
> `(button-label button)' is evaluated, there is no button and this
> signals the error.

That what was wrong then.
 
> If you want to use the existing Help buffer, just remove the call to
> with-help-window in qrh-b. 


> However, Help buffers are read-only, so
> trying to insert text will raise another error. To avoid this, you can
> let-bind buffer-read-only in qrh-b. 

I do not experience the problem you mention.  What error are you referring to, 
and how can it be triggered ?

> However, since qrh-a inserts "[FC]"
> but qrh-b tries to match "[FA]", the match will fail, so the insertion
> in qrh-b will not happen. - Steve Berman

That was an error from my part.

Re: Using button-label in pcase

[Stephen Berman]

On Mon, 24 Jul 2023 21:35:44 +0000 uzibalqa <uzibalqa@proton.me> wrote:

> ------- Original Message -------
> On Tuesday, July 25th, 2023 at 8:07 AM, Stephen Berman
> <stephen.berman@gmx.net> wrote:
>
>
>> On Mon, 24 Jul 2023 19:14:27 +0000 uzibalqa uzibalqa@proton.me wrote:
>>
>> > Want to print some text as a result of clicking a button. With the code below
>> > I end up with
>> >
>> > (wrong-type-argument integer-or-marker-p nil)
>> > buffer-substring-no-properties(nil nil)
>> > button-label(#<overlay in no buffer>)
>> > (let* ((val (button-label button))) (if (equal val '"[FA]") (let nil
>> > (insert qrh-c))))
>> > (closure ((button . #<overlay in no buffer>)) nil (let* ((val
>> > (button-label button))) (if (equal val '"[FA]") (let nil (insert
>> > qrh-c)))))()
>> > help--window-setup("Help" (closure ((button . #<overlay in no buffer>))
>> > nil (let* ((val (button-label button))) (if (equal val '"[FA]") (let nil
>> > (insert qrh-c))))))
>> > qrh-b(#<overlay in no buffer>)
>> > button-activate(#<overlay in no buffer> t)
>> > push-button(3 t)
>> >
>> > What is going on. Is there a fix?
>> >
>> > (defconst qrh-c "[FA] Some Text")
>> >
>> > (defun qrh-b (button)
>> > "Prints information about how to install emacs."
>> > (with-help-window (help-buffer)
>> > (pcase (button-label button)
>> > ("[FA]" (insert qrh-c))) ))
>> >
>> > (defun qrh-a ()
>> > "Prints information about how to install emacs."
>> > (interactive)
>> > (with-help-window (help-buffer)
>> > (insert-button "[FC]"
>> > 'action 'qrh-b 'follow-link t) ))
>>
>> The error is raised because qrh-b calls with-help-window with the Help
>> buffer current, but with-help-window erases the buffer, so when
>> `(button-label button)' is evaluated, there is no button and this
>> signals the error.
>
> That what was wrong then.

That there was no button.  When you execute your command qrh-a and then
in the resulting *Help* buffer press the button, it disappears.

>> If you want to use the existing Help buffer, just remove the call to
>> with-help-window in qrh-b.
>
>
>> However, Help buffers are read-only, so
>> trying to insert text will raise another error. To avoid this, you can
>> let-bind buffer-read-only in qrh-b.
>
> I do not experience the problem you mention.  What error are you referring to,
> and how can it be triggered ?

Did you remove the call the with-help-window in qrh-b and correct the
match condtion (or change the string in qrh-a to match the one in
qrh-b)?  If so, then when you press the button in the *Help* buffer, you
will get the error "Buffer is read-only: #<buffer *Help*>".

Steve Berman

Re: Using button-label in pcase

[uzibalqa]

------- Original Message -------
On Tuesday, July 25th, 2023 at 9:51 AM, Stephen Berman <stephen.berman@gmx.net> wrote:


> On Mon, 24 Jul 2023 21:35:44 +0000 uzibalqa uzibalqa@proton.me wrote:
> 
> > ------- Original Message -------
> > On Tuesday, July 25th, 2023 at 8:07 AM, Stephen Berman
> > stephen.berman@gmx.net wrote:
> > 
> > > On Mon, 24 Jul 2023 19:14:27 +0000 uzibalqa uzibalqa@proton.me wrote:
> > > 
> > > > Want to print some text as a result of clicking a button. With the code below
> > > > I end up with
> > > > 
> > > > (wrong-type-argument integer-or-marker-p nil)
> > > > buffer-substring-no-properties(nil nil)
> > > > button-label(#<overlay in no buffer>)
> > > > (let* ((val (button-label button))) (if (equal val '"[FA]") (let nil
> > > > (insert qrh-c))))
> > > > (closure ((button . #<overlay in no buffer>)) nil (let* ((val
> > > > (button-label button))) (if (equal val '"[FA]") (let nil (insert
> > > > qrh-c)))))()
> > > > help--window-setup("Help" (closure ((button . #<overlay in no buffer>))
> > > > nil (let* ((val (button-label button))) (if (equal val '"[FA]") (let nil
> > > > (insert qrh-c))))))
> > > > qrh-b(#<overlay in no buffer>)
> > > > button-activate(#<overlay in no buffer> t)
> > > > push-button(3 t)
> > > > 
> > > > What is going on. Is there a fix?
> > > > 
> > > > (defconst qrh-c "[FA] Some Text")
> > > > 
> > > > (defun qrh-b (button)
> > > > "Prints information about how to install emacs."
> > > > (with-help-window (help-buffer)
> > > > (pcase (button-label button)
> > > > ("[FA]" (insert qrh-c))) ))
> > > > 
> > > > (defun qrh-a ()
> > > > "Prints information about how to install emacs."
> > > > (interactive)
> > > > (with-help-window (help-buffer)
> > > > (insert-button "[FC]"
> > > > 'action 'qrh-b 'follow-link t) ))
> > > 
> > > The error is raised because qrh-b calls with-help-window with the Help
> > > buffer current, but with-help-window erases the buffer, so when
> > > `(button-label button)' is evaluated, there is no button and this
> > > signals the error.
> > 
> > That what was wrong then.
> 
> 
> That there was no button. When you execute your command qrh-a and then
> in the resulting Help buffer press the button, it disappears.
> 
> > > If you want to use the existing Help buffer, just remove the call to
> > > with-help-window in qrh-b.
> > 
> > > However, Help buffers are read-only, so
> > > trying to insert text will raise another error. To avoid this, you can
> > > let-bind buffer-read-only in qrh-b.
> > 
> > I do not experience the problem you mention. What error are you referring to,
> > and how can it be triggered ?
> 
> Did you remove the call the with-help-window in qrh-b and correct the
> match condtion (or change the string in qrh-a to match the one in
> qrh-b)? If so, then when you press the button in the Help buffer, you
> will get the error "Buffer is read-only: #<buffer Help>".
 
> Steve Berman

I did the changes and have the following

  (pcase (button-label button)
    ("[FA]" 
       (with-help-window (help-buffer)  ; Print in help buffer
         (insert qrh-c)))

Re: Using button-label in pcase

[Stephen Berman]

On Mon, 24 Jul 2023 22:24:33 +0000 uzibalqa <uzibalqa@proton.me> wrote:

> ------- Original Message -------
> On Tuesday, July 25th, 2023 at 9:51 AM, Stephen Berman
> <stephen.berman@gmx.net> wrote:
>
>
>> On Mon, 24 Jul 2023 21:35:44 +0000 uzibalqa uzibalqa@proton.me wrote:
>>
>> > ------- Original Message -------
>> > On Tuesday, July 25th, 2023 at 8:07 AM, Stephen Berman
>> > stephen.berman@gmx.net wrote:
>> >
>> > > On Mon, 24 Jul 2023 19:14:27 +0000 uzibalqa uzibalqa@proton.me wrote:
>> > >
>> > > > Want to print some text as a result of clicking a button. With the code below
>> > > > I end up with
>> > > >
>> > > > (wrong-type-argument integer-or-marker-p nil)
>> > > > buffer-substring-no-properties(nil nil)
>> > > > button-label(#<overlay in no buffer>)
>> > > > (let* ((val (button-label button))) (if (equal val '"[FA]") (let nil
>> > > > (insert qrh-c))))
>> > > > (closure ((button . #<overlay in no buffer>)) nil (let* ((val
>> > > > (button-label button))) (if (equal val '"[FA]") (let nil (insert
>> > > > qrh-c)))))()
>> > > > help--window-setup("Help" (closure ((button . #<overlay in no buffer>))
>> > > > nil (let* ((val (button-label button))) (if (equal val '"[FA]") (let nil
>> > > > (insert qrh-c))))))
>> > > > qrh-b(#<overlay in no buffer>)
>> > > > button-activate(#<overlay in no buffer> t)
>> > > > push-button(3 t)
>> > > >
>> > > > What is going on. Is there a fix?
>> > > >
>> > > > (defconst qrh-c "[FA] Some Text")
>> > > >
>> > > > (defun qrh-b (button)
>> > > > "Prints information about how to install emacs."
>> > > > (with-help-window (help-buffer)
>> > > > (pcase (button-label button)
>> > > > ("[FA]" (insert qrh-c))) ))
>> > > >
>> > > > (defun qrh-a ()
>> > > > "Prints information about how to install emacs."
>> > > > (interactive)
>> > > > (with-help-window (help-buffer)
>> > > > (insert-button "[FC]"
>> > > > 'action 'qrh-b 'follow-link t) ))
>> > >
>> > > The error is raised because qrh-b calls with-help-window with the Help
>> > > buffer current, but with-help-window erases the buffer, so when
>> > > `(button-label button)' is evaluated, there is no button and this
>> > > signals the error.
>> >
>> > That what was wrong then.
>>
>>
>> That there was no button. When you execute your command qrh-a and then
>> in the resulting Help buffer press the button, it disappears.
>>
>> > > If you want to use the existing Help buffer, just remove the call to
>> > > with-help-window in qrh-b.
>> >
>> > > However, Help buffers are read-only, so
>> > > trying to insert text will raise another error. To avoid this, you can
>> > > let-bind buffer-read-only in qrh-b.
>> >
>> > I do not experience the problem you mention. What error are you referring to,
>> > and how can it be triggered ?
>>
>> Did you remove the call the with-help-window in qrh-b and correct the
>> match condtion (or change the string in qrh-a to match the one in
>> qrh-b)? If so, then when you press the button in the Help buffer, you
>> will get the error "Buffer is read-only: #<buffer Help>".
>
>> Steve Berman
>
> I did the changes and have the following
>
>   (pcase (button-label button)
>     ("[FA]"
>        (with-help-window (help-buffer)  ; Print in help buffer
>          (insert qrh-c)))

Sure, that's a fine way to avoid the problem with the read-only state of
the *Help* buffer.

Steve Berman

Re: Using button-label in pcase

[uzibalqa]

------- Original Message -------
On Tuesday, July 25th, 2023 at 10:36 AM, Stephen Berman <stephen.berman@gmx.net> wrote:


> On Mon, 24 Jul 2023 22:24:33 +0000 uzibalqa uzibalqa@proton.me wrote:
> 
> > ------- Original Message -------
> > On Tuesday, July 25th, 2023 at 9:51 AM, Stephen Berman
> > stephen.berman@gmx.net wrote:
> > 
> > > On Mon, 24 Jul 2023 21:35:44 +0000 uzibalqa uzibalqa@proton.me wrote:
> > > 
> > > > ------- Original Message -------
> > > > On Tuesday, July 25th, 2023 at 8:07 AM, Stephen Berman
> > > > stephen.berman@gmx.net wrote:
> > > > 
> > > > > On Mon, 24 Jul 2023 19:14:27 +0000 uzibalqa uzibalqa@proton.me wrote:
> > > > > 
> > > > > > Want to print some text as a result of clicking a button. With the code below
> > > > > > I end up with
> > > > > > 
> > > > > > (wrong-type-argument integer-or-marker-p nil)
> > > > > > buffer-substring-no-properties(nil nil)
> > > > > > button-label(#<overlay in no buffer>)
> > > > > > (let* ((val (button-label button))) (if (equal val '"[FA]") (let nil
> > > > > > (insert qrh-c))))
> > > > > > (closure ((button . #<overlay in no buffer>)) nil (let* ((val
> > > > > > (button-label button))) (if (equal val '"[FA]") (let nil (insert
> > > > > > qrh-c)))))()
> > > > > > help--window-setup("Help" (closure ((button . #<overlay in no buffer>))
> > > > > > nil (let* ((val (button-label button))) (if (equal val '"[FA]") (let nil
> > > > > > (insert qrh-c))))))
> > > > > > qrh-b(#<overlay in no buffer>)
> > > > > > button-activate(#<overlay in no buffer> t)
> > > > > > push-button(3 t)
> > > > > > 
> > > > > > What is going on. Is there a fix?
> > > > > > 
> > > > > > (defconst qrh-c "[FA] Some Text")
> > > > > > 
> > > > > > (defun qrh-b (button)
> > > > > > "Prints information about how to install emacs."
> > > > > > (with-help-window (help-buffer)
> > > > > > (pcase (button-label button)
> > > > > > ("[FA]" (insert qrh-c))) ))
> > > > > > 
> > > > > > (defun qrh-a ()
> > > > > > "Prints information about how to install emacs."
> > > > > > (interactive)
> > > > > > (with-help-window (help-buffer)
> > > > > > (insert-button "[FC]"
> > > > > > 'action 'qrh-b 'follow-link t) ))
> > > > > 
> > > > > The error is raised because qrh-b calls with-help-window with the Help
> > > > > buffer current, but with-help-window erases the buffer, so when
> > > > > `(button-label button)' is evaluated, there is no button and this
> > > > > signals the error.
> > > > 
> > > > That what was wrong then.
> > > 
> > > That there was no button. When you execute your command qrh-a and then
> > > in the resulting Help buffer press the button, it disappears.
> > > 
> > > > > If you want to use the existing Help buffer, just remove the call to
> > > > > with-help-window in qrh-b.
> > > > 
> > > > > However, Help buffers are read-only, so
> > > > > trying to insert text will raise another error. To avoid this, you can
> > > > > let-bind buffer-read-only in qrh-b.
> > > > 
> > > > I do not experience the problem you mention. What error are you referring to,
> > > > and how can it be triggered ?
> > > 
> > > Did you remove the call the with-help-window in qrh-b and correct the
> > > match condtion (or change the string in qrh-a to match the one in
> > > qrh-b)? If so, then when you press the button in the Help buffer, you
> > > will get the error "Buffer is read-only: #<buffer Help>".
> > 
> > > Steve Berman
> > 
> > I did the changes and have the following
> > 
> > (pcase (button-label button)
> > ("[FA]"
> > (with-help-window (help-buffer) ; Print in help buffer
> > (insert qrh-c)))
> 
> 
> Sure, that's a fine way to avoid the problem with the read-only state of
> the Help buffer.
> 
> Steve Berman

I replicated the error you mentioned though.  Why does it happen ?  Is that because
the insert would be within an (with-help-window (help-buffer) ?

Re: Using button-label in pcase

[Stephen Berman]

On Mon, 24 Jul 2023 22:40:03 +0000 uzibalqa <uzibalqa@proton.me> wrote:

> ------- Original Message -------
> On Tuesday, July 25th, 2023 at 10:36 AM, Stephen Berman
> <stephen.berman@gmx.net> wrote:
>
>
>> On Mon, 24 Jul 2023 22:24:33 +0000 uzibalqa uzibalqa@proton.me wrote:
>>
>> > ------- Original Message -------
>> > On Tuesday, July 25th, 2023 at 9:51 AM, Stephen Berman
>> > stephen.berman@gmx.net wrote:
>> >
>> > > On Mon, 24 Jul 2023 21:35:44 +0000 uzibalqa uzibalqa@proton.me wrote:
>> > >
>> > > > ------- Original Message -------
>> > > > On Tuesday, July 25th, 2023 at 8:07 AM, Stephen Berman
>> > > > stephen.berman@gmx.net wrote:
>> > > >
>> > > > > On Mon, 24 Jul 2023 19:14:27 +0000 uzibalqa uzibalqa@proton.me wrote:
>> > > > >
>> > > > > > Want to print some text as a result of clicking a button. With the
>> > > > > > code below
>> > > > > > I end up with
>> > > > > >
>> > > > > > (wrong-type-argument integer-or-marker-p nil)
>> > > > > > buffer-substring-no-properties(nil nil)
>> > > > > > button-label(#<overlay in no buffer>)
>> > > > > > (let* ((val (button-label button))) (if (equal val '"[FA]") (let nil
>> > > > > > (insert qrh-c))))
>> > > > > > (closure ((button . #<overlay in no buffer>)) nil (let* ((val
>> > > > > > (button-label button))) (if (equal val '"[FA]") (let nil (insert
>> > > > > > qrh-c)))))()
>> > > > > > help--window-setup("Help" (closure ((button . #<overlay in no buffer>))
>> > > > > > nil (let* ((val (button-label button))) (if (equal val '"[FA]") (let nil
>> > > > > > (insert qrh-c))))))
>> > > > > > qrh-b(#<overlay in no buffer>)
>> > > > > > button-activate(#<overlay in no buffer> t)
>> > > > > > push-button(3 t)
>> > > > > >
>> > > > > > What is going on. Is there a fix?
>> > > > > >
>> > > > > > (defconst qrh-c "[FA] Some Text")
>> > > > > >
>> > > > > > (defun qrh-b (button)
>> > > > > > "Prints information about how to install emacs."
>> > > > > > (with-help-window (help-buffer)
>> > > > > > (pcase (button-label button)
>> > > > > > ("[FA]" (insert qrh-c))) ))
>> > > > > >
>> > > > > > (defun qrh-a ()
>> > > > > > "Prints information about how to install emacs."
>> > > > > > (interactive)
>> > > > > > (with-help-window (help-buffer)
>> > > > > > (insert-button "[FC]"
>> > > > > > 'action 'qrh-b 'follow-link t) ))
>> > > > >
>> > > > > The error is raised because qrh-b calls with-help-window with the Help
>> > > > > buffer current, but with-help-window erases the buffer, so when
>> > > > > `(button-label button)' is evaluated, there is no button and this
>> > > > > signals the error.
>> > > >
>> > > > That what was wrong then.
>> > >
>> > > That there was no button. When you execute your command qrh-a and then
>> > > in the resulting Help buffer press the button, it disappears.
>> > >
>> > > > > If you want to use the existing Help buffer, just remove the call to
>> > > > > with-help-window in qrh-b.
>> > > >
>> > > > > However, Help buffers are read-only, so
>> > > > > trying to insert text will raise another error. To avoid this, you can
>> > > > > let-bind buffer-read-only in qrh-b.
>> > > >
>> > > > I do not experience the problem you mention. What error are you referring to,
>> > > > and how can it be triggered ?
>> > >
>> > > Did you remove the call the with-help-window in qrh-b and correct the
>> > > match condtion (or change the string in qrh-a to match the one in
>> > > qrh-b)? If so, then when you press the button in the Help buffer, you
>> > > will get the error "Buffer is read-only: #<buffer Help>".
>> >
>> > > Steve Berman
>> >
>> > I did the changes and have the following
>> >
>> > (pcase (button-label button)
>> > ("[FA]"
>> > (with-help-window (help-buffer) ; Print in help buffer
>> > (insert qrh-c)))
>>
>>
>> Sure, that's a fine way to avoid the problem with the read-only state of
>> the Help buffer.
>>
>> Steve Berman
>
> I replicated the error you mentioned though.  Why does it happen ?  Is that because
> the insert would be within an (with-help-window (help-buffer) ?

I get no error using the last code snippet you provided, because the
button-label is evaluated before with-help-window erases the buffer, and
with-help-window makes the *Help* buffer temporarily writeable.

Steve Berman

Re: Using button-label in pcase

[uzibalqa]

------- Original Message -------
On Tuesday, July 25th, 2023 at 10:53 AM, Stephen Berman <stephen.berman@gmx.net> wrote:


> On Mon, 24 Jul 2023 22:40:03 +0000 uzibalqa uzibalqa@proton.me wrote:
> 
> > ------- Original Message -------
> > On Tuesday, July 25th, 2023 at 10:36 AM, Stephen Berman
> > stephen.berman@gmx.net wrote:
> > 
> > > On Mon, 24 Jul 2023 22:24:33 +0000 uzibalqa uzibalqa@proton.me wrote:
> > > 
> > > > ------- Original Message -------
> > > > On Tuesday, July 25th, 2023 at 9:51 AM, Stephen Berman
> > > > stephen.berman@gmx.net wrote:
> > > > 
> > > > > On Mon, 24 Jul 2023 21:35:44 +0000 uzibalqa uzibalqa@proton.me wrote:
> > > > > 
> > > > > > ------- Original Message -------
> > > > > > On Tuesday, July 25th, 2023 at 8:07 AM, Stephen Berman
> > > > > > stephen.berman@gmx.net wrote:
> > > > > > 
> > > > > > > On Mon, 24 Jul 2023 19:14:27 +0000 uzibalqa uzibalqa@proton.me wrote:
> > > > > > > 
> > > > > > > > Want to print some text as a result of clicking a button. With the
> > > > > > > > code below
> > > > > > > > I end up with
> > > > > > > > 
> > > > > > > > (wrong-type-argument integer-or-marker-p nil)
> > > > > > > > buffer-substring-no-properties(nil nil)
> > > > > > > > button-label(#<overlay in no buffer>)
> > > > > > > > (let* ((val (button-label button))) (if (equal val '"[FA]") (let nil
> > > > > > > > (insert qrh-c))))
> > > > > > > > (closure ((button . #<overlay in no buffer>)) nil (let* ((val
> > > > > > > > (button-label button))) (if (equal val '"[FA]") (let nil (insert
> > > > > > > > qrh-c)))))()
> > > > > > > > help--window-setup("Help" (closure ((button . #<overlay in no buffer>))
> > > > > > > > nil (let* ((val (button-label button))) (if (equal val '"[FA]") (let nil
> > > > > > > > (insert qrh-c))))))
> > > > > > > > qrh-b(#<overlay in no buffer>)
> > > > > > > > button-activate(#<overlay in no buffer> t)
> > > > > > > > push-button(3 t)
> > > > > > > > 
> > > > > > > > What is going on. Is there a fix?
> > > > > > > > 
> > > > > > > > (defconst qrh-c "[FA] Some Text")
> > > > > > > > 
> > > > > > > > (defun qrh-b (button)
> > > > > > > > "Prints information about how to install emacs."
> > > > > > > > (with-help-window (help-buffer)
> > > > > > > > (pcase (button-label button)
> > > > > > > > ("[FA]" (insert qrh-c))) ))
> > > > > > > > 
> > > > > > > > (defun qrh-a ()
> > > > > > > > "Prints information about how to install emacs."
> > > > > > > > (interactive)
> > > > > > > > (with-help-window (help-buffer)
> > > > > > > > (insert-button "[FC]"
> > > > > > > > 'action 'qrh-b 'follow-link t) ))
> > > > > > > 
> > > > > > > The error is raised because qrh-b calls with-help-window with the Help
> > > > > > > buffer current, but with-help-window erases the buffer, so when
> > > > > > > `(button-label button)' is evaluated, there is no button and this
> > > > > > > signals the error.
> > > > > > 
> > > > > > That what was wrong then.
> > > > > 
> > > > > That there was no button. When you execute your command qrh-a and then
> > > > > in the resulting Help buffer press the button, it disappears.
> > > > > 
> > > > > > > If you want to use the existing Help buffer, just remove the call to
> > > > > > > with-help-window in qrh-b.
> > > > > > 
> > > > > > > However, Help buffers are read-only, so
> > > > > > > trying to insert text will raise another error. To avoid this, you can
> > > > > > > let-bind buffer-read-only in qrh-b.
> > > > > > 
> > > > > > I do not experience the problem you mention. What error are you referring to,
> > > > > > and how can it be triggered ?
> > > > > 
> > > > > Did you remove the call the with-help-window in qrh-b and correct the
> > > > > match condtion (or change the string in qrh-a to match the one in
> > > > > qrh-b)? If so, then when you press the button in the Help buffer, you
> > > > > will get the error "Buffer is read-only: #<buffer Help>".
> > > > 
> > > > > Steve Berman
> > > > 
> > > > I did the changes and have the following
> > > > 
> > > > (pcase (button-label button)
> > > > ("[FA]"
> > > > (with-help-window (help-buffer) ; Print in help buffer
> > > > (insert qrh-c)))
> > > 
> > > Sure, that's a fine way to avoid the problem with the read-only state of
> > > the Help buffer.
> > > 
> > > Steve Berman
> > 
> > I replicated the error you mentioned though. Why does it happen ? Is that because
> > the insert would be within an (with-help-window (help-buffer) ?
> 
> 
> I get no error using the last code snippet you provided, because the
> button-label is evaluated before with-help-window erases the buffer, and
> with-help-window makes the Help buffer temporarily writeable.
> 
> Steve Berman

It's all good then.  Felicitations.