A current limitation of doctest is that it can't handle 
output containing blank lines, since it uses blank 
lines to detect the end of the example.

This patch uses adds special "blank line marker" to 
mark blank lines in the expected output.  In order to 
distinguish this marker from actual output, it must be 
dedented such that it ends just before the doctest 
example's indentation.

Here's an example use, with BLANKLINE_MARKER set 
to "-" (as it is in the patch):

def _test_blankline_marker():
    r"""
    This test example uses BLANKLINE_MARKER to 
    signify a blank line:

        >>> print 'first line\n\nthis is after a blank line'
        first line
       -
        this is after a blank line
        >>> print 'trailing blanks can be marked too\n'
        trailing blanks can be marked too
       -
    """

If desired, BLANKLINE_MARKER could be changed to 
another string. (This is an option for the developers 
of doctest, *not* for users.) E.g., here's the same 
example with BLANKLINE_MARKER="BL>":

def _test_blankline_marker():
    r"""
    This test example uses BLANKLINE_MARKER to 
    signify a blank line:

        >>> print 'first line\n\nthis is after a blank line'
        first line
     BL>
        this is after a blank line
        >>> print 'trailing blanks can be marked too\n'
        trailing blanks can be marked too
     BL>
    """

In the patch, the indentation rules for 
BLANKLINE_MARKER are fairly strict: it must be 
dedented to end one character before the indentation 
defined by the doctest example's prompt (>>>).  
But if desired, we could relax this restriction, and say 
that it simply has to be dedented further than the 
prompt.  E.g., this would make the following legal (it 
currently is not):

def _test_blankline_marker():
    r"""
    This test example uses BLANKLINE_MARKER to 
    signify a blank line:

        >>> print 'first line\n\nthis is after a blank line'
        first line
    -
        this is after a blank line
        >>> print 'trailing blanks can be marked too\n'
        trailing blanks can be marked too
    -
    """

This patch is probably mutually exclusive with patch 
#932933 [1], since they both have the same goal: to 
allow blank lines in doctest output.  I thought of the 
other solution first, but I think I prefer this patch. 
Here's a comparison of pros and cons of this patch vs 
#932933.

  [+] it doesn't need a special option to turn it on
  [+] it handles trailing blank lines
  [+] it won't break external tools like epytext and
      restructuredtext that look for doctest blocks.
  [-] the user must manually add blank line markers.

[1] <http://sourceforge.net/tracker/index.php?
func=detail&aid=932933&group_id=5470&atid=3054
70>

The patch was made avainst revision 1.33 of 
doctest.py.  If this patch looks good, I'd be happy to 
write a patch for docs & test cases.

Logged In: YES 
user_id=195958

I just noticed that sourceforge strips leading whitespace 
from every line.  (Why does it do that?)  You should be 
able to reconstruct what the examples should look like 
from the text, but if not, here's the first example with 
leading spaces replaced by periods:

def _test_blankline_marker():
....r"""
....This test example uses BLANKLINE_MARKER to signify
....a blank line:
....
........>>> print 'first line\n\nthis is after a blank line'
........first line
.......-
........this is after a blank line
........>>> print 'trailing blanks can be marked too\n'
........trailing blank lines can be marked too
.......-
...."""

Logged In: YES 
user_id=21627

This patch is incomplete: It lacks changes to the
documentation (libdoctest.tex) and to the test suite
(test_libdoctest.tex).

Pasting examples into the patch submission is futile: they
are lost once the patch is accepted. So if you think users
of your patch should know them, you should incorporate them
into your patch - if not in the documentation, then perhaps
in the Demo directory.

Please submit a single patch file containing all changes.

SF has not stripped the indentation; if you look at the HTML
source, you'll see it is still there. However, in HTML,
indentation is stripped by the web browsers. That is one
reason why the submission guidelines say not to include the
code in the description.

Logged In: YES 
user_id=469548

Edward, it seems like recent doctest checkins have addressed
this, so I'm closing this. Please reopen if I'm mistaken.