sage.rings.polynomial.multi_polynomial_ring_base: Add ABC BooleanPolynomialRing_base (fixup)

Author: Matthias Koeppe

src/sage/rings/polynomial/multi_polynomial_ring_base.pyx

@@ -1738,6 +1738,28 @@ cdef class MPolynomialRing_base(sage.rings.ring.CommutativeRing):
         return DifferentialWeylAlgebra(self)
 
 
+cdef class BooleanPolynomialRing_base(MPolynomialRing_base):
+    r"""
+    Abstract base class for :class:`~sage.rings.polynomial.pbori.pbori.BooleanPolynomialRing`.
+
+    This class is defined for the purpose of ``isinstance`` tests.  It should not be
+    instantiated.
+
+    EXAMPLES::
+
+        sage: from sage.rings.polynomial.multi_polynomial_ring_base import BooleanPolynomialRing_base
+        sage: R.<x, y, z> = BooleanPolynomialRing()
+        sage: isinstance(R, BooleanPolynomialRing_base)
+        True
+
+    By design, there is only one direct implementation subclass::
+
+        sage: len(BooleanPolynomialRing_base.__subclasses__()) <= 1
+        True
+    """
+    pass
+
+
 ####################
 # Leave *all* old versions!
 

src/sage/rings/polynomial/pbori/pbori.pxd

@@ -1,6 +1,6 @@
 from libcpp.memory cimport unique_ptr, shared_ptr, make_shared
 
-from sage.rings.polynomial.multi_polynomial_ring_base cimport BooleanPolynomialRing_base
+from sage.rings.polynomial.multi_polynomial_ring_base cimport MPolynomialRing_base, BooleanPolynomialRing_base
 from sage.rings.polynomial.multi_polynomial cimport MPolynomial
 from sage.structure.element cimport MonoidElement
 

src/sage/rings/polynomial/pbori/pbori.pyx

@@ -257,7 +257,7 @@ block_dp_asc = int(pbblock_dp_asc)
 rings = sage.misc.weak_dict.WeakValueDictionary()
 
 
-cdef class BooleanPolynomialRing(MPolynomialRing_base):
+cdef class BooleanPolynomialRing(BooleanPolynomialRing_base):
     """
     Construct a boolean polynomial ring with the following parameters:
 
@@ -410,7 +410,7 @@ cdef class BooleanPolynomialRing(MPolynomialRing_base):
             pbnames = tuple(names)
             names = [name.replace('(', '').replace(')', '') for name in pbnames]
 
-        MPolynomialRing_base.__init__(self, GF((2,1)), n, names, order)
+        BooleanPolynomialRing_base.__init__(self, GF((2,1)), n, names, order)
 
         counter = 0
         for i in range(len(order.blocks()) - 1):
@@ -7645,7 +7645,7 @@ cdef BooleanPolynomialRing BooleanPolynomialRing_from_PBRing(PBRing _ring):
 
     self._pbring = _ring
 
-    MPolynomialRing_base.__init__(self, GF(2), n, names, T)
+    BooleanPolynomialRing_base.__init__(self, GF(2), n, names, T)
 
     self._zero_element = new_BP(self)
     (<BooleanPolynomial>self._zero_element)._pbpoly = PBBoolePolynomial(0, self._pbring)