Make it possible to use direct C++ code

  1. The pplpy library does not support extension type construction from an already constructed C++ object. The following construction should be supported
from ppl.ppl_decl cimport PPL_Variable
from ppl.linear_algebra cimport Variable
cdef PPL_Variable * x = new PPL_Variable(0)
cdef Variable py_x = Variable.__new__(Variable)
py_x.thisptr = x

The reason why it is not currently possible is that the initialization is done within the __cinit__ method instead of __init__.

  1. Most of the binary operators are not declared in ppl_decl.pxd. It is for example impossible to create linear expression from pure C++.
Edited by Vincent Delecroix