bug#3238: python mode comments should define indentation level

[Akkana Peck]

In python mode (python.el), I'm having a lot of trouble adding comments
because newline-and-indent always re-indents to the level of the last
code line, ignoring comment lines.

For instance, if I have this code:

    for item in items :
        for c in chars :
            do_stuff()
            # hitting return after do_stuff() will indent 12 spaces

    # But I want to start a comment block with a 4-space indent.
    # Here is the start of a comment describing what the next code block does.
    # Each of these lines is indented 12 spaces, not 4.

When I hit return after the do_stuff() line, I'm indented 12 spaces,
which is reasonable given the context. I backspace 8 chars to where I
actually want to be. If I now type a code line, like i = 10, and hit
return, the next line will be indented 4 spaces. But if I type a comment
line like the one shown in my example, the next line will be indented
12 spaces, not 4. So it's difficult to add comments for functions or
blocks of code, because you have to correct the indentation with
every line you type.

newline-and-indent in python mode should do the same thing from comment
lines as it does from code lines: use the indentation of the current line.


In GNU Emacs 22.2.1 (i486-pc-linux-gnu, GTK+ Version 2.14.1)
 of 2008-09-05 on vernadsky, modified by Ubuntu
Windowing system distributor `The X.Org Foundation', version 11.0.10502000
configured using `configure  '--build=i486-linux-gnu' '--host=i486-linux-gnu' 
'--prefix=/usr' '--sharedstatedir=/var/lib' '--libexecdir=/usr/lib' 
'--localstatedir=/var' '--infodir=/usr/share/info' '--mandir=/usr/share/man' 
'--with-pop=yes' 
'--enable-locallisppath=/etc/emacs22:/etc/emacs:/usr/local/share/emacs/22.2/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/22.2/site-lisp:/usr/share/emacs/site-lisp:/usr/share/emacs/22.2/leim'
 '--with-x=yes' '--with-x-toolkit=gtk' 'build_alias=i486-linux-gnu' 
'host_alias=i486-linux-gnu' 'CFLAGS=-DDEBIAN -DSITELOAD_PURESIZE_EXTRA=5000 -g 
-O2' 'LDFLAGS=-g -Wl,--as-needed' 'CPPFLAGS=''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: C
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8
  default-enable-multibyte-characters: t

Major mode: Python

Minor modes in effect:
  tooltip-mode: t
  mouse-wheel-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  unify-8859-on-encoding-mode: t
  utf-translate-cjk-mode: t
  line-number-mode: t
  transient-mark-mode: identity

Recent input:
C-b C-b C-w C-x C-s <help-echo> C-u C-v C-u C-v C-n 
C-n C-n C-n C-n C-a C-k C-k C-p C-p C-y C-p <tab> C-n 
C-a C-k C-k C-x C-f <tab> <tab> C-g C-x C-f s h a <tab> 
<return> C-s d e l e t e C-n C-x b <return> <return> 
C-h C-h C-h C-h g i m p . d e l e t e ( n e w i m g 
) C-x C-s C-p <return> C-h C-h C-h C-h # SPC I f SPC 
t h e SPC s a v e SPC w a s SPC s u c c e s s f u l 
, SPC w e SPC d o n ' t SPC n e e d SPC t o SPC s h 
o w SPC t h e SPC n e w SPC i m a g e , <return> C-h 
C-h C-h C-h # SPC s o SPC d e l e t e SPC i t : C-x 
C-s C-n C-n C-a <return> C-x C-s C-x b <return> C-x 
k <return> C-x b <return> <next> <next> <down-mouse-1> 
<mouse-1> C-h . <return> C-h C-h C-h C-h # SPC C-x 
C-f C-w C-h / . e m a c s <return> C-x b <return> C-x 
C-s X X X C-x C-s C-h C-h C-h C-x C-s C-x b <return> 
C-s p y t h o n C-s C-s C-s C-s C-a C-x b <return> 
C-h C-h C-h SPC a s d f SPC a s d f SPC a s d f a s 
SPC d f a s d SPC f a s d SPC f a s d SPC f a s d f 
M-q M-x r e p o t C-h r t - e m <tab> <return>

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