On Wed, 28 Nov 2012 14:08:15 -0600, Evan Driscoll wrote:
> I'm only entering this thread now so I'm not really in context, but
> you're correct; in Python 3, -tt is set by default, which makes illegal
> mixing an error.
>
> However, not all mixing is illegal: what it means by "code that
> illegally mixes tabs and spaces" is "code whose interpretation differs
> depending upon the interpretation of the tab width". While I'm not going
> to go test it, I think that if you, say, indent from the first to the
> second level with tabs (consistently), indent from the second to third
> level with spaces (consistently), and indent from the third to fourth
> level with tabs (consistently), it should not complain.
Correct, which disappoints me. Testing with Python 3:
py> if True:
... if True: # tab
... pass # tab, then four spaces
...
py>
I would prefer that the "pass" line would fail with an illegal indent,
but it does not. But at least the following fails cleanly:
py> if True:
... if True: # tab
... pass # tab, then four spaces
... pass # two spaces, tab, four spaces
File "<stdin>", line 4
pass # two spaces, tab, four spaces
^
TabError: inconsistent use of tabs and spaces in indentation
> Or perhaps I
> should say "it should complain that you're a bad person and should feel
> bad, but it won't." :-) (In fact, you could indent one block at the
> second level with tabs and another with spaces.)
I don't mind different blocks using different indentation. You have
always been able to do this:
py> if True:
... pass # eight spaces
...
py> if True:
... pass # two spaces
...
py>
If you don't like that, don't do it! Consistent indentation globally per
file is a matter for coding conventions. However, I think that within a
single block, Python should enforce "all tabs" or "all spaces".
Perhaps it would be nice if Python honoured a directive setting indent
style to spaces or indents, as it honours source code encoding lines:
# -*- indent: <mode> -*-
Where <mode> could be one of:
space[s] Only accept spaces in indentation
tab[s] Only accept tabs in indentation
mixed Accept "mixed" tabs and spaces, but only if consistent
with mixed the default for backward compatibility.
--
Steven
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