Trac #33558: get rid of __nonzero__ and use __bool__ instead

as this is the official python3 choice

the first 2 commits were scripted

other commits are hand-made, finishing the task

URL: https://trac.sagemath.org/33558
Reported by: chapoton
Ticket author(s): Frédéric Chapoton
Reviewer(s): Travis Scrimshaw

src/doc/en/thematic_tutorials/coercion_and_categories.rst

@@ -1503,7 +1503,7 @@ The elements have to provide more::
 
 Hence, the elements must provide ``denominator()`` and ``numerator()``
 methods, and must be able to tell whether they are zero or not. The base class
-:class:`~sage.structure.element.Element` provides a default ``__nonzero__()``
+:class:`~sage.structure.element.Element` provides a default ``__bool__()``
 method. In addition, the elements may provide Sage's single underscore
 arithmetic methods (actually any ring element *should* provide them).
 

src/sage/algebras/commutative_dga.py

@@ -551,7 +551,7 @@ def _is_nonzero(self):
         """
         Return ``True`` iff this morphism is nonzero.
 
-        This is used by the :meth:`Morphism.__nonzero__` method, which
+        This is used by the :meth:`Morphism.__bool__` method, which
         in turn is used by the :func:`TestSuite` test
         ``_test_nonzero_equal``.
 

src/sage/algebras/jordan_algebra.py

@@ -411,7 +411,7 @@ def __bool__(self):
             """
             return bool(self._x)
 
-        __nonzero__ = __bool__
+
 
         def __eq__(self, other):
             """
@@ -834,7 +834,7 @@ def __bool__(self):
             """
             return bool(self._s) or bool(self._v)
 
-        __nonzero__ = __bool__
+
 
         def __eq__(self, other):
             """

src/sage/algebras/letterplace/free_algebra_element_letterplace.pyx

@@ -399,7 +399,7 @@ cdef class FreeAlgebraElement_letterplace(AlgebraElement):
         """
         return self._poly.lc()
 
-    def __nonzero__(self):
+    def __bool__(self):
         """
         TESTS::
 

src/sage/algebras/lie_algebras/classical_lie_algebra.py

@@ -1346,7 +1346,7 @@ def __bool__(self):
             """
             return bool(self._real) or bool(self._imag)
 
-        __nonzero__ = __bool__
+
 
         def __hash__(self):
             r"""

src/sage/algebras/lie_algebras/lie_algebra_element.pyx

@@ -260,7 +260,7 @@ cdef class LieAlgebraElementWrapper(ElementWrapper):
          ├┼┘
          └┘
     """
-    def __nonzero__(self):
+    def __bool__(self):
         """
         Return if ``self`` is non-zero.
 
@@ -1151,7 +1151,7 @@ cdef class UntwistedAffineLieAlgebraElement(Element):
                                self._c_coeff, self._d_coeff))
         return self._hash
 
-    def __nonzero__(self):
+    def __bool__(self):
         """
         Return ``self`` as a boolean.
 

src/sage/algebras/quatalg/quaternion_algebra_element.pyx

@@ -323,7 +323,7 @@ cdef class QuaternionAlgebraElement_abstract(AlgebraElement):
             return Rational(self[0])
         raise TypeError
 
-    def __nonzero__(self):
+    def __bool__(self):
         """
         Return ``True`` if this quaternion is nonzero.
 
@@ -946,7 +946,7 @@ cdef class QuaternionAlgebraElement_rational_field(QuaternionAlgebraElement_abst
         """
         return not (mpz_sgn(self.y) or mpz_sgn(self.z) or mpz_sgn(self.w))
 
-    def __nonzero__(self):
+    def __bool__(self):
         """
         Return True if this quaternion is nonzero.
 

src/sage/categories/crystals.py

@@ -2198,7 +2198,7 @@ def __bool__(self):
         """
         return any(self._on_gens(mg) is not None for mg in self._gens)
 
-    __nonzero__ = __bool__
+
 
     # TODO: Does this belong in the element_class of the Crystals() category?
     def to_module_generator(self, x):

src/sage/categories/examples/commutative_additive_monoids.py

@@ -126,6 +126,6 @@ def __bool__(self):
             """
             return any(x for x in self.value.values())
 
-        __nonzero__ = __bool__
+
 
 Example = FreeCommutativeAdditiveMonoid

src/sage/categories/examples/lie_algebras.py

@@ -207,7 +207,7 @@ def __bool__(self):
             """
             return bool(self.value)
 
-        __nonzero__ = __bool__
+
 
         def _add_(self, rhs):
             """

src/sage/categories/homset.py

@@ -743,7 +743,7 @@ def __bool__(self):
         """
         return True
 
-    __nonzero__ = __bool__
+
 
     def homset_category(self):
         """

src/sage/categories/morphism.pyx

@@ -411,7 +411,7 @@ cdef class Morphism(Map):
             domain = <Parent?>base
         return rich_to_bool(op, 0)
 
-    def __nonzero__(self):
+    def __bool__(self):
         r"""
         Return whether this morphism is not a zero morphism.
 

src/sage/categories/rings.py

@@ -193,7 +193,7 @@ def _is_nonzero(self):
             .. NOTE::
 
                 We can not override ``is_zero()`` from the category framework
-                and we can not implement ``__nonzero__`` because it is a
+                and we can not implement ``__bool__`` because it is a
                 special method. That this is why this has a cumbersome name.
 
             EXAMPLES::
@@ -202,7 +202,6 @@ def _is_nonzero(self):
                 True
                 sage: ZZ.hom(Zmod(1))._is_nonzero()
                 False
-
             """
             return bool(self.codomain().one())
 

src/sage/combinat/combinat.py

@@ -1404,7 +1404,7 @@ def __bool__(self) -> bool:
         """
         return bool(self._list)
 
-    __nonzero__ = __bool__
+
 
     def __len__(self) -> Integer:
         """

src/sage/combinat/crystals/kirillov_reshetikhin.py

@@ -4158,4 +4158,3 @@ def is_isomorphism(self):
     is_embedding = is_isomorphism
     is_strict = is_isomorphism
     __bool__ = is_isomorphism
-    __nonzero__ = is_isomorphism

src/sage/combinat/finite_state_machine.py

@@ -2012,7 +2012,7 @@ def __bool__(self):
         """
         return True  # A state cannot be zero (see __init__)
 
-    __nonzero__ = __bool__
+
 
     def _epsilon_successors_(self, fsm=None):
         """
@@ -2491,7 +2491,7 @@ def __bool__(self):
         """
         return True  # A transition cannot be zero (see __init__)
 
-    __nonzero__ = __bool__
+
 
 
 # ****************************************************************************
@@ -3932,7 +3932,7 @@ def __bool__(self):
         """
         return bool(self._states_)
 
-    __nonzero__ = __bool__
+
 
     def __eq__(self, other):
         """

src/sage/combinat/recognizable_series.py

@@ -872,7 +872,7 @@ def __bool__(self):
                 return False
         return True
 
-    __nonzero__ = __bool__
+
 
     def transposed(self):
         r"""

src/sage/combinat/rigged_configurations/rigged_partition.pyx

@@ -290,7 +290,7 @@ cdef class RiggedPartition(SageObject):
             self._hash = hash(tuple(self._list))
         return self._hash
 
-    def __nonzero__(self):
+    def __bool__(self):
         """
         TESTS::
 

src/sage/combinat/words/word_char.pyx

@@ -122,7 +122,7 @@ cdef class WordDatatype_char(WordDatatype):
         if self._is_slice == 0:
             sig_free(self._data)
 
-    def __nonzero__(self):
+    def __bool__(self):
         r"""
         Test whether the word is not empty.
 

src/sage/cpython/debugimpl.c

@@ -233,11 +233,7 @@ static void _type_debug(PyTypeObject* tp)
         subattr_pointer_meth(tp_as_number, nb_negative, "__neg__");
         subattr_pointer_meth(tp_as_number, nb_positive, "__pos__");
         subattr_pointer_meth(tp_as_number, nb_absolute, "__abs__");
-        #if PY_MAJOR_VERSION <= 2
-            subattr_pointer_meth(tp_as_number, nb_nonzero, "__nonzero__");
-        #else
-            subattr_pointer_meth(tp_as_number, nb_bool, "__bool__");
-        #endif
+        subattr_pointer_meth(tp_as_number, nb_bool, "__bool__");
         subattr_pointer_meth(tp_as_number, nb_invert, "__invert__");
         subattr_pointer_meth(tp_as_number, nb_lshift, "__lshift__");
         subattr_pointer_meth(tp_as_number, nb_rshift, "__rshift__");

src/sage/data_structures/bounded_integer_sequences.pyx

@@ -769,7 +769,7 @@ cdef class BoundedIntegerSequence:
         """
         return self.data.length
 
-    def __nonzero__(self):
+    def __bool__(self):
         """
         A bounded integer sequence is nonzero if and only if its length is nonzero.
 

src/sage/features/__init__.py

@@ -371,7 +371,7 @@ def __bool__(self):
         """
         return bool(self.is_present)
 
-    __nonzero__ = __bool__
+
 
     def __repr__(self):
         r"""

src/sage/groups/abelian_gps/abelian_group.py

@@ -662,7 +662,7 @@ def __bool__(self):
         """
         return not self.is_trivial()
 
-    __nonzero__ = __bool__
+
 
     @cached_method
     def dual_group(self, names="X", base_ring=None):

src/sage/interfaces/fricas.py

@@ -1145,7 +1145,7 @@ def __bool__(self):
         P = self._check_valid()
         return not P.new("zero?(%s)" % self._name).sage()
 
-    __nonzero__ = __bool__
+
 
     def __float__(self):
         """

src/sage/interfaces/gap.py

@@ -936,7 +936,7 @@ def __bool__(self):
         P = self._check_valid()
         return self != P(0) and repr(self) != 'false'
 
-    __nonzero__ = __bool__
+
 
     def __len__(self):
         """

src/sage/interfaces/gp.py

@@ -957,7 +957,7 @@ def __bool__(self):
         P = self._check_valid()
         return P.eval('%s != 0'%(self.name())) == '1'
 
-    __nonzero__ = __bool__
+
 
     def _complex_mpfr_field_(self, CC):
         """

src/sage/interfaces/interface.py

@@ -1337,7 +1337,7 @@ def __bool__(self):
                             P._false_symbol())
         return P.eval(cmd) != P._true_symbol()
 
-    __nonzero__ = __bool__
+
 
     def __float__(self):
         """

src/sage/interfaces/kash.py

@@ -738,7 +738,7 @@ def __bool__(self):
         # Kash has separate integer and boolean types, and FALSE does not
         # compare equal to 0 (i.e, FALSE = 0 is FALSE)
 
-        # Python 2.x uses __nonzero__ for type conversion to 'bool', so we
+        # Python 3.x uses __bool__ for type conversion to 'bool', so we
         # have to test against FALSE, and sage.structure.element.Element's
         # default implementation of is_zero() is to return 'not self', so
         # our boolean conversion also has to test against 0.
@@ -747,8 +747,6 @@ def __bool__(self):
         return (P.eval('%s = FALSE' % self.name()) == 'FALSE' and
                 P.eval('%s = 0' % self.name()) == 'FALSE')
 
-    __nonzero__ = __bool__
-
     def _sage_(self, locals={}, *args):
         """
         Convert this object to Sage.

src/sage/interfaces/lisp.py

@@ -434,7 +434,7 @@ def __bool__(self):
         """
         return self != 0 and repr(self) != 'NIL'
 
-    __nonzero__ = __bool__
+
 
     def _add_(self, right):
         """

src/sage/interfaces/macaulay2.py

@@ -1179,7 +1179,7 @@ def __bool__(self):
         P = self.parent()
         return P.eval('{0}===false or {0}==0'.format(self._name)) != 'true'
 
-    __nonzero__ = __bool__
+
 
     def sage_polystring(self):
         """

src/sage/interfaces/magma.py

@@ -2651,7 +2651,7 @@ def __bool__(self):
                 pass
         return True
 
-    __nonzero__ = __bool__
+
 
     def sub(self, gens):
         """

src/sage/interfaces/mathematica.py

@@ -1037,7 +1037,7 @@ def __bool__(self):
         cmd = '%s===%s' % (self._name, P._false_symbol())
         return P.eval(cmd).strip() != P._true_symbol()
 
-    __nonzero__ = __bool__
+
 
     def n(self, *args, **kwargs):
         r"""

src/sage/interfaces/mathics.py

@@ -1248,7 +1248,7 @@ def __bool__(self):
         cmd = '%s===%s' % (self._name, P._false_symbol())
         return not str(P(cmd)) == P._true_symbol()
 
-    __nonzero__ = __bool__
+
 
     def n(self, *args, **kwargs):
         r"""

src/sage/interfaces/maxima_abstract.py

@@ -1150,7 +1150,7 @@ def __bool__(self):
         # but be careful, since for relations things like is(equal(a,b)) are
         # what Maxima needs
 
-    __nonzero__ = __bool__
+
 
     def _richcmp_(self, other, op):
         """

src/sage/interfaces/octave.py

@@ -659,7 +659,7 @@ def __bool__(self):
         """
         return str(self) != ' [](0x0)' and any(x != '0' for x in str(self).split())
 
-    __nonzero__ = __bool__
+
 
     def _matrix_(self, R=None):
         r"""

src/sage/interfaces/polymake.py

@@ -1082,7 +1082,7 @@ def __bool__(self):
         cmd = '{} {} {};'.format(self._name, P._equality_symbol(), t)
         return P.get(cmd) == t
 
-    __nonzero__ = __bool__
+
 
     def known_properties(self):
         """

src/sage/interfaces/r.py

@@ -1605,7 +1605,7 @@ def __bool__(self):
         """
         return "FALSE" in repr(self==0)
 
-    __nonzero__ = __bool__
+
 
     def _comparison(self, other, symbol):
         """