Pickling tests.

tests/run/reduce_pickle.pyx

+cdef class A:
+    """
+    >>> a = A(3); a
+    A(3)
+    >>> import cPickle
+    >>> cPickle.loads(cPickle.dumps(a))
+    A(3)
+    >>> import pickle
+    >>> pickle.loads(pickle.dumps(a))
+    A(3)
+    """
+
+    cdef int value
+
+    def __init__(self, value):
+        self.value = value
+
+    def __repr__(self):
+        return "A(%s)" % self.value
+
+    def __reduce__(self):
+        return A, (self.value,)
+
+cdef class B:
+    """
+    >>> b = B(x=37, y=389); b
+    B(x=37, y=389)
+    >>> import cPickle
+    >>> cPickle.loads(cPickle.dumps(b))
+    B(x=37, y=389)
+    >>> import pickle
+    >>> pickle.loads(pickle.dumps(b))
+    B(x=37, y=389)
+    """
+
+    cdef int x, y
+
+    def __init__(self, x=0, y=0):
+        self.x = x
+        self.y = y
+
+    def __repr__(self):
+        return "B(x=%s, y=%s)" % (self.x, self.y)
+
+    def __reduce__(self):
+        return makeB, ({'x': self.x, 'y': self.y},)
+
+def makeB(kwds):
+    return B(**kwds)