bug#40563: 28.0.50; Narrow to defun in python buffer

bug#40563: 28.0.50; Narrow to defun in python buffer

[Tomas Nordin]

Hello Buglist

emacs Q

Find file class.py with this content

----------------------------------8<----------------------------------
"""Try narrow to defun on class"""


class A():

    def a1(self):
        pass

    def a2(self):
        pass


class B():

    def b1(self):
        pass

    def b2(self):
        pass
---------------------------------->8----------------------------------

Move point to bol on class A
C-x n d

result:
----------------------------------8<----------------------------------
lass A():

    def a1(self):
        pass

    def a2(self):
        pass
---------------------------------->8----------------------------------

notice the 'c' is gone

C-x n w

Move point to bol on class B

C-x n d

result:
----------------------------------8<----------------------------------
    def b2(self):
        pass
---------------------------------->8----------------------------------

I then noticed that placing point just below the class definition and
then narrow works as expected. But I think the recipe way should work as
well. And even if not, this behavior is confusing.

Best regards
--
Tomas

In GNU Emacs 28.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.5, cairo version 1.16.0)
 of 2020-04-01 built on fliptop
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bug#40563: 28.0.50; Narrow to defun in python buffer

[Lars Ingebrigtsen]

Tomas Nordin <tomasn@posteo.net> writes:

> I then noticed that placing point just below the class definition and
> then narrow works as expected. But I think the recipe way should work as
> well. And even if not, this behavior is confusing.

This bug is still present on the trunk.

The problem is most easily reproduced by calling the

  (python-nav--beginning-of-defun)

function directly.  If point is on the first line, then this function
won't do the right thing:

def a1(self):
    pass

Because it starts off checking whether it is, indeed, on the first line
before trying to get to the start of the first line in the function.

This seems like such a basic problem that I wondered whether it's a
newly introduced bug, but it's been there for...  at least a decade,
apparently?

Doesn't anybody use python-mode?

It looks easy enough to fix, but I'm just wondering whether there's
something obvious here I'm not seeing.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#40563: 28.0.50; Narrow to defun in python buffer

[Tomas Nordin]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> Tomas Nordin <tomasn@posteo.net> writes:
>
>> I then noticed that placing point just below the class definition and
>> then narrow works as expected. But I think the recipe way should work as
>> well. And even if not, this behavior is confusing.
>
> This bug is still present on the trunk.
>
> The problem is most easily reproduced by calling the
>
>   (python-nav--beginning-of-defun)
>
> function directly.  If point is on the first line, then this function
> won't do the right thing:
>
> def a1(self):
>     pass
>

It does the right thing here (still on the same build) when point is at
column > 4, and the wrong thing when at 4 or less. Indentation?

--
Tomas

bug#40563: 28.0.50; Narrow to defun in python buffer

[Tomas Nordin]

Tomas Nordin <tomasn@posteo.net> writes:

> Lars Ingebrigtsen <larsi@gnus.org> writes:
>
>> Tomas Nordin <tomasn@posteo.net> writes:
>>
>>> I then noticed that placing point just below the class definition and
>>> then narrow works as expected. But I think the recipe way should work as
>>> well. And even if not, this behavior is confusing.
>>
>> This bug is still present on the trunk.
>>
>> The problem is most easily reproduced by calling the
>>
>>   (python-nav--beginning-of-defun)
>>
>> function directly.  If point is on the first line, then this function
>> won't do the right thing:
>>
>> def a1(self):
>>     pass
>>
>
> It does the right thing here (still on the same build) when point is at
> column > 4, and the wrong thing when at 4 or less. Indentation?

Or I said wrong, now my version is 28.0.50 2020-06-07.

bug#40563: 28.0.50; Narrow to defun in python buffer

[Andreas Röhler]

On 01.12.20 22:05, Tomas Nordin wrote:
> Tomas Nordin <tomasn@posteo.net> writes:
>
>> Lars Ingebrigtsen <larsi@gnus.org> writes:
>>
>>> Tomas Nordin <tomasn@posteo.net> writes:
>>>
>>>> I then noticed that placing point just below the class definition and
>>>> then narrow works as expected. But I think the recipe way should work as
>>>> well. And even if not, this behavior is confusing.
>>> This bug is still present on the trunk.
>>>
>>> The problem is most easily reproduced by calling the
>>>
>>>    (python-nav--beginning-of-defun)
>>>
>>> function directly.  If point is on the first line, then this function
>>> won't do the right thing:
>>>
>>> def a1(self):
>>>      pass
>>>
>> It does the right thing here (still on the same build) when point is at
>> column > 4, and the wrong thing when at 4 or less. Indentation?
> Or I said wrong, now my version is 28.0.50 2020-06-07.
>
>

May reproduce this with

GNU Emacs 28.0.50 (build 1, i686-pc-linux-gnu, GTK+ Version 3.14.5, 
cairo version 1.14.0) of 2020-11-19

bug#40563: 28.0.50; Narrow to defun in python buffer

[Tomas Nordin]

[-- Attachment #1: Type: text/plain, Size: 1388 bytes --]

Hello

Lars Ingebrigtsen <larsi@gnus.org> writes:

> Tomas Nordin <tomasn@posteo.net> writes:
>
>> I then noticed that placing point just below the class definition and
>> then narrow works as expected. But I think the recipe way should work as
>> well. And even if not, this behavior is confusing.
>
> This bug is still present on the trunk.
>
> The problem is most easily reproduced by calling the
>
>   (python-nav--beginning-of-defun)
>
> function directly.  If point is on the first line, then this function
> won't do the right thing:
>
> def a1(self):
>     pass

Attached is a patch that fix the problems described in this report. The
change of variable name 'beg-indentation' to 'body-indentation' is not
part of the fix, but something I did during study making it easier for
me to understand the meaning of it. Feel free to disagree on that
change. The naming beg-indentation does not re-occur in python.el

The patch mean to say it might be necessary to move forward on the line
before search if point start off at the beginning of the defun, to allow
re-search-backward to succeed on the intended place.

The patch fixes this report, but it doesn't allow narrowing nested
python defuns (like a def in a class). For that I think it is necassary
to look at narrow-to-defun. I intend to suggest something about that in
another report.

What do you think?

Best regards
--
Tomas


[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: beginning-of-defun.patch --]
[-- Type: text/x-diff, Size: 2024 bytes --]

diff --git a/lisp/progmodes/python.el b/lisp/progmodes/python.el
index e9c3b3986a..32ffc5a9d6 100644
--- a/lisp/progmodes/python.el
+++ b/lisp/progmodes/python.el
@@ -1404,7 +1404,7 @@ python-nav--beginning-of-defun
          (line-beg-pos (line-beginning-position))
          (line-content-start (+ line-beg-pos (current-indentation)))
          (pos (point-marker))
-         (beg-indentation
+         (body-indentation
           (and (> arg 0)
                (save-excursion
                  (while (and
@@ -1415,9 +1415,16 @@ python-nav--beginning-of-defun
                      0))))
          (found
           (progn
-            (when (and (< arg 0)
-                       (python-info-looking-at-beginning-of-defun))
+            (when (and (python-info-looking-at-beginning-of-defun)
+                       (or (< arg 0)
+                           ;; If looking at beginning of defun, and if
+                           ;; pos is > line-content-start, ensure a
+                           ;; backward re search match this defun by
+                           ;; going to end of line before calling
+                           ;; re-search-fn bug#40563
+                           (and (> arg 0) (> pos line-content-start))))
               (end-of-line 1))
+
             (while (and (funcall re-search-fn
                                  python-nav-beginning-of-defun-regexp nil t)
                         (or (python-syntax-context-type)
@@ -1425,7 +1432,7 @@ python-nav--beginning-of-defun
                             ;; backwards by checking indentation.
                             (and (> arg 0)
                                  (not (= (current-indentation) 0))
-                                 (>= (current-indentation) beg-indentation)))))
+                                 (>= (current-indentation) body-indentation)))))
             (and (python-info-looking-at-beginning-of-defun)
                  (or (not (= (line-number-at-pos pos)
                              (line-number-at-pos)))

bug#40563: 28.0.50; Narrow to defun in python buffer

[Lars Ingebrigtsen]

Tomas Nordin <tomasn@posteo.net> writes:

> The patch fixes this report, but it doesn't allow narrowing nested
> python defuns (like a def in a class). For that I think it is necassary
> to look at narrow-to-defun. I intend to suggest something about that in
> another report.
>
> What do you think?

Looks good to me (and it fixes the bug described in this bug report), so
I've now applied the patch to Emacs 28.

This change was small enough to apply without assigning copyright to the
FSF, but for future patches you want to submit, it might make sense to
get the paperwork started now, so that subsequent patches can be applied
speedily. Would you be willing to sign such paperwork?

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#40563: 28.0.50; Narrow to defun in python buffer

[Tomas Nordin]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> Tomas Nordin <tomasn@posteo.net> writes:
>
>> The patch fixes this report, but it doesn't allow narrowing nested
>> python defuns (like a def in a class). For that I think it is necassary
>> to look at narrow-to-defun. I intend to suggest something about that in
>> another report.
>>
>> What do you think?
>
> Looks good to me (and it fixes the bug described in this bug report), so
> I've now applied the patch to Emacs 28.

Thanks

>
> This change was small enough to apply without assigning copyright to
the
> FSF, but for future patches you want to submit, it might make sense to
> get the paperwork started now, so that subsequent patches can be applied
> speedily. Would you be willing to sign such paperwork?

Yes, surely. Please paper me.

--
Tomas

bug#40563: 28.0.50; Narrow to defun in python buffer

[Lars Ingebrigtsen]

Tomas Nordin <tomasn@posteo.net> writes:

>> This change was small enough to apply without assigning copyright to
> the
>> FSF, but for future patches you want to submit, it might make sense to
>> get the paperwork started now, so that subsequent patches can be applied
>> speedily. Would you be willing to sign such paperwork?
>
> Yes, surely. Please paper me.

Great; here's the form to get started:

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bug#40563: 28.0.50; Narrow to defun in python buffer

[Tomas Nordin]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> Tomas Nordin <tomasn@posteo.net> writes:
>
>>> This change was small enough to apply without assigning copyright to
>> the
>>> FSF, but for future patches you want to submit, it might make sense to
>>> get the paperwork started now, so that subsequent patches can be applied
>>> speedily. Would you be willing to sign such paperwork?
>>
>> Yes, surely. Please paper me.
>
> Great; here's the form to get started:

Sent