Folks,

I am setting out to Cythonize a function, and found that Cython does
not appear to support tuple unpacking in function arguments. This is
perfectly legal Python:

def test_tuple_unpack((x_1, y_1), (x_2, y_2)):
        print x_1, y_1, x_2, y_2

but when I try to run Cython on it:

$ cython tuple_unpack_args.pyx

Error compiling Cython file:
------------------------------------------------------------
...
def test_nested_tuples((x_1, y_1), (x_2, y_2)):
                          ^
------------------------------------------------------------

tuple_unpack_args.pyx:1:27: Expected ')', found ','

$ cython --version
Cython version 0.17.1

Whether we want to support this I don't know, but if the goal is to be
able to compile all legal python, then this is a missing feature.

-Chris

--

Christopher Barker, Ph.D.
Oceanographer

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Chris.Bar...@noaa.gov

Chris Barker, 09.11.2012 01:51:

Python 2, to be exact.

Well, it's a known limitation at least.

http://trac.cython.org/cython_trac/ticket/692

Given that it's a dead feature that requires a dedicated, non-trivial
implementation (unnamed function arguments) but that is very easy to work
around, there hasn't been any move to support it yet.

Stefan

I see -- I've paid far too little attention to Python 3 -- I didn't
realize this was depreciated.

I should have searched the tickets, clearly!

But maybe it should be mentioned here:

http://docs.cython.org/src/userguide/limitations.html

(which has nothing in it now!)

or at least the ticket could be assigned to the "Python Semantics"
component, so it will show up here:

http://trac.cython.org/cython_trac/query?status=assigned&status=new&s...

Should I do that? I _think_ I have TRAC access.

Fair enough.

-thx.
  -Chris

--

Christopher Barker, Ph.D.
Oceanographer

Emergency Response Division
NOAA/NOS/OR&R            (206) 526-6959   voice
7600 Sand Point Way NE   (206) 526-6329   fax
Seattle, WA  98115       (206) 526-6317   main reception

Chris.Bar...@noaa.gov

Chris Barker, 09.11.2012 20:33:

AFAIR, there was some content a while ago, but it became outdated and was
removed, likely around 0.15 when the last major Python features went in.

Good call, I've changed the "Component".

Stefan