Cython: declaring a typedefed enum

[Jernej Azarija]

Dear sage-devel,

I have another question related to Cython. I like to post them here instead of cython-users as it seems to me that the former is a much slower group. That said....

The definition of the Graph class in one of the libraries is :

===================================
class Graph : public AbstractGraph
{
public:
  typedef enum {
    shs_f = 0, shs_fs, shs_fl, shs_fm, shs_fsm, shs_flm
  } SplittingHeuristic;
// blah blah blah

}
===================================

Following Cython's guide on this subject http://docs.cython.org/src/userguide/external_C_code.html I figured my definition of the wrapped class should look like:

===================================
# blah blah blah
cdef cppclass Graph(AbstractGraph):
        ctypedef enum SplittingHeuristic:
           shs_f = 0
# blah blah blah
===================================



Unfortunately, this gives me a compilation error:

===================================
    cdef cppclass Graph(AbstractGraph):
        ctypedef enum SplittingHeuristic:
                     ^
------------------------------------------------------------

sage/graphs/bliss.pyx:45:22: Syntax error in C variable declaration
===================================

Now I think the pasted code completely isolates the issue since I am able to work with the Graph class (access methods) normally. The only issue appears when I introduce this enum thing. Hence I am wondering what exactly I am missing in this code?


Best,

Jernej

[Volker Braun]

Don't redeclare the enum values. 

cdef cppclass Graph(AbstractGraph):

        ctypedef enum SplittingHeuristic:

           shs_f

           foo

           bar

[Volker Braun]

Also, Cython doesn't support class-level typedefs so you'll probably need a version of the "literal" trick:

ctypedef enum Graph_SplittingHeuristic "Graph::SplittingHeuristic":

    shs_f

    foo

    bar

[Jernej Azarija]

Volker,

this gives me the exact same error:

========
    cdef cppclass Graph(AbstractGraph):

        ctypedef enum Graph_SplittingHeuristic "Graph::SplittingHeuristic":

                     ^
------------------------------------------------------------

sage/graphs/bliss.pyx:36:22: Syntax error in C variable declaration
========

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[Volker Braun]

You need to move the typedef outside of the class scope, see my second post.

[Jernej Azarija]

Looks like we're on the right track - though it now seems  to not recognize the scope of this enum  within the library?

=====
build/cythonized/sage/graphs/bliss.cpp: In function 'bliss::Graph* __pyx_f_4sage_6graphs_5bliss_bliss_graph(PyObject*, PyObject*, PyObject*, PyObject*)':
build/cythonized/sage/graphs/bliss.cpp:1895:38: error: 'shs_f' is not a member of 'bliss'
   __pyx_v_g->set_splitting_heuristic(bliss::shs_f);
                                      ^
error: command 'gcc' failed with exit status 1
====