[Python-bugs-list] [ python-Bugs-587239 ] python-mode and nested indents
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Bugs item #587239, was opened at 2002-07-26 15:56
Message generated for change (Comment added) made by montanaro
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Category: Demos and Tools
Group: None
>Status: Closed
Resolution: None
Priority: 5
Submitted By: Andrew Koenig (arkoenig)
Assigned to: Barry A. Warsaw (bwarsaw)
Summary: python-mode and nested indents
Initial Comment:
Using Python-mode 4.6 and GNU emacs 21.2.2, I enter the
following:
if x < 0:
for i in range(100):
print i
else:
print "x is negative"
If I now put the cursor on the "else:" line and hit
tab, it erroneously changes the indentation to line the
"else" up with the "for" above it.
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>Comment By: Skip Montanaro (montanaro)
Date: 2003-08-04 22:10
Message:
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Migrating to the new python-mode project. You can
follow it here:
https://sourceforge.net/tracker/
index.php?func=detail&aid=783235&group_id=86916&ati
d=581349
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Comment By: Tim Peters (tim_one)
Date: 2002-07-26 17:40
Message:
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It's up to Barry to decide (and I assigned the report to
him). I'll only add that the behavior does appear to be as
documented:
"""
The \[indent-for-tab-command] and \[py-newline-and-
indent] keys try to suggest plausible indentation, based on
the indentation of preceding statements.
[example snipped]
Python-mode cannot know whether that's what you
intended, or whether
\tif a > 0:
\t c = d
\t_
was your intent. In general, Python-mode either
reproduces the indentation of the (closest code or
indenting-comment) preceding statement, or adds an extra
py-indent-offset blanks if the preceding statement has `:' as
its last significant (non-whitespace and non-comment)
character. If the suggested indentation is too much, use
\[py-electric-backspace] to reduce it.
""
That seems (to me) easy to remember and to live with.
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Comment By: Andrew Koenig (arkoenig)
Date: 2002-07-26 17:14
Message:
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If you really believe that hitting tab means that the block
structure isn't what you intended, then you should also
believe that hitting tab repeatedly on a line that can
legally be indented in exactly two different ways
(presumably with different meanings) should cycle between
the meanings. Which it doesn't in this case.
I am willing to accept that hitting tab should generate the
maximum legal indent, which would mean that the behavior I
described with "else:" isn't a bug. I do think, though,
that generating an illegal indent should be considered a
bug. I also think that for most cases, lining up an "else"
with the nearest preceding "if" or "elif" rather than the
nearest preceding "for" or "while" is less surprising,
though I'll admit that's a matter of taste.
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Comment By: Tim Peters (tim_one)
Date: 2002-07-26 17:05
Message:
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I agree that the second one (elif) may be considered a
bug. Afraid I can't agree aboiut the first reason, though: of
course hitting tab in pymode can change the meaning.
When you've got
if whatever:
->x
y
and hit tab when on the line containing y, it assumes you're
hitting tab for a reason, not just to make trouble <wink>.
I believe there's a discussion about this in the long form of
the pymode help. Since pymod can't *know* the block
structure you intend, it does its best to guess, and hitting
a "guess the block structure I intended" key is taken as
meaning, for a start, that the block structure on the current
line isn't what you intended (else why would have hit the
key? as a Python programmer, you should already know
this isn't C mode <wink>).
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Comment By: Andrew Koenig (arkoenig)
Date: 2002-07-26 16:49
Message:
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Frankly, I hadn't thought of that possibility!
However, I still consider the behavior a bug, for two
reasons: (1) I can type something that's syntactically
valid, hit tab, and have it change the meaning of what I
typed, and (2) It changes the indentation in the same way if
I say "elif:" instead of "else:", even though that change is
not syntactically valid. That is (using -> to indicate a
tab):
if x < 0:
->for i in range(100):
->->print i
elif x > 0:
->print x
Again, hitting tab on the "elif" line will indent the "elif"
to line up with the "for", even though the result is
syntactically invalid.
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Comment By: Tim Peters (tim_one)
Date: 2002-07-26 16:14
Message:
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Andrew, why is that erroneous? Loops in Python have
(optional) "else:" clauses too. There's no way for pymode to
guess whether you intended the else to go with the if or the
for. I expect it looks backward for the closest-preceding
construct the else-statement could "belong to", and finds
the for-loop first.
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