Closes gh-6863.
This triggers a PendingDeprecationWarning in py3.5 -- you're supposed to just write "return" instead (which on earlier versions is equivalent). See PEP 479: https://www.python.org/dev/peps/pep-0479/
The rules enforced are the same as those used for scipy.
Some of those problems look like potential coding errors. In those cases a Fixme comment was made and the offending code, usually an unused variable, was commented out.
The idioms fixer makes the following replacements. 1) int <- bool 2) comparison or identity of types <- isinstance 3) a.sort() <- sorted(a) There were two problems that needed to be dealt with after the application of the fixer. First, the replacement of comparison or identity of types by isinstance was not always correct. The isinstance function returns true for subtypes whereas many of the places where the fixer made a substitution needed to check for exact type equality. Second, the sorted function was applied to arrays, but because it treats them as iterators and constructs a sorted list from the result, that is the wrong thing to do. Closes #3062.
The numliterals fixer replaces the old style octal number like '01' by '0o1' removes the 'L' suffix. Octal values were previously mistakenly specified in some dates, those uses have been corrected by removing the leading zeros. Simply Removing the 'L' suffix should not be a problem, but in some testing code it looks neccesary, so in those places the Python long constructor is used instead. The 'long' type is no longer defined in Python 3. Because we need to have it defined for Python 2 it is added to numpy/compat/np3k.py where it is defined as 'int' for Python 3 and 'long' for Python 2. The `long` fixer then needs to be skipped so that it doesn't undo the good work. Closes #3074, #3067.
MAINT: Cleanup some imports involving reduce.
Add `print_function` to all `from __future__ import ...` statements and use the python3 print function syntax everywhere. Closes #3078.
Because reduce has been available in functools since Python 2.6 we can get rid of the version checks we currently have before we import it. Also removes some reduce related skips in tools/py3tool.py. We were already skipping the reduce fixer so this has no effect other than cleaning up the code.