[C++-sig] undefined symbols with def_readonly

[Neal Becker]

I have:

struct turbo_enc_1_15 {
...
  static const int TAIL_BITS = 2*MEMORY;
...

Then this wrapper:
BOOST_PYTHON_MODULE(turbo_enc_1_15)
{
  class_<turbo_enc_1_15> ("turbo_enc_1_15", no_init)
...
    .def_readonly ("TAIL_BITS", &turbo_enc_1_15::TAIL_BITS)
    ;

At runtime I get this:
ImportError: ../mod/turbo_enc_1_15.so: undefined symbol: _ZN14turbo_enc_1_159TAIL_BITSE

Anything obviously wrong here?