src/sage/rings/morphism.pyx: Remove class and function deprecated in #23204 (2017)

Author: Matthias Koeppe

src/sage/rings/morphism.pyx

@@ -413,29 +413,6 @@ from sage.structure.richcmp cimport (richcmp, rich_to_bool)
 from sage.misc.cachefunc import cached_method
 
 
-def is_RingHomomorphism(phi):
-    """
-    Return ``True`` if ``phi`` is of type :class:`RingHomomorphism`.
-
-    EXAMPLES::
-
-        sage: f = Zmod(8).cover()
-        sage: sage.rings.morphism.is_RingHomomorphism(f)
-        doctest:warning
-        ...
-        DeprecationWarning: is_RingHomomorphism() should not be used anymore. Check whether the category_for() your morphism is a subcategory of Rings() instead.
-        See https://github.com/sagemath/sage/issues/23204 for details.
-        True
-        sage: sage.rings.morphism.is_RingHomomorphism(2/3)
-        False
-    """
-    sage.misc.superseded.deprecation(23204, "is_RingHomomorphism() should not be used anymore. Check whether the category_for() your morphism is a subcategory of Rings() instead.")
-    # We use the category framework to determine whether something is a ring homomorphism.
-    from sage.categories.map import Map
-    from sage.categories.rings import Rings
-    return isinstance(phi, Map) and phi.category_for().is_subcategory(Rings())
-
-
 cdef class RingMap(Morphism):
     """
     Set-theoretic map between rings.
@@ -1682,120 +1659,6 @@ cdef class RingHomomorphism(RingMap):
         return self.is_injective() and self.is_surjective()
 
 
-cdef class RingHomomorphism_coercion(RingHomomorphism):
-    r"""
-    A ring homomorphism that is a coercion.
-
-    .. WARNING::
-
-        This class is obsolete. Set the category of your morphism to a
-        subcategory of ``Rings`` instead.
-
-    TESTS:
-
-        sage: from sage.rings.morphism import RingHomomorphism_coercion
-        sage: parent = Hom(ZZ,ZZ)
-        sage: f = parent.__make_element_class__(RingHomomorphism_coercion)(parent)
-        doctest:warning
-        ...
-        DeprecationWarning: Set the category of your morphism to a subcategory of Rings instead.
-        See https://github.com/sagemath/sage/issues/23204 for details.
-        sage: TestSuite(f).run()
-
-    """
-    def __init__(self, parent, check=True):
-        r"""
-        TESTS:
-
-            sage: from sage.rings.morphism import RingHomomorphism_coercion
-            sage: parent = Hom(ZZ,ZZ)
-            sage: f = parent.__make_element_class__(RingHomomorphism_coercion)(parent)
-            doctest:warning
-            ...
-            DeprecationWarning: Set the category of your morphism to a subcategory of Rings instead.
-            See https://github.com/sagemath/sage/issues/23204 for details.
-            sage: isinstance(f, RingHomomorphism_coercion)
-            True
-
-        """
-        sage.misc.superseded.deprecation(23204, "Set the category of your morphism to a subcategory of Rings instead.")
-
-        RingHomomorphism.__init__(self, parent)
-        # putting in check allows us to define subclasses of RingHomomorphism_coercion that implement _coerce_map_from
-        if check and not self.codomain().has_coerce_map_from(self.domain()):
-            raise TypeError("Natural coercion morphism from %s to %s not defined."%(self.domain(), self.codomain()))
-
-    def _repr_type(self):
-        """
-        Used internally when printing this.
-
-        EXAMPLES::
-
-            sage: from sage.rings.morphism import RingHomomorphism_coercion
-            sage: parent = Hom(ZZ,ZZ)
-            sage: f = parent.__make_element_class__(RingHomomorphism_coercion)(parent)
-            sage: f._repr_type()
-            'Ring Coercion'
-
-        """
-        return "Ring Coercion"
-
-    cpdef _richcmp_(self, other, int op):
-        """
-        Compare a ring coercion morphism ``self`` to ``other``.
-
-        Ring coercion morphisms never compare equal to any other data type. If
-        other is a ring coercion morphism, the parents of ``self`` and
-        ``other`` are compared.
-
-        EXAMPLES::
-
-            sage: from sage.rings.morphism import RingHomomorphism_coercion
-            sage: parent = Hom(ZZ,ZZ)
-            sage: f = parent.__make_element_class__(RingHomomorphism_coercion)(parent)
-            sage: f == f
-            True
-            sage: f != f
-            False
-        """
-        if not isinstance(other, RingHomomorphism_coercion):
-            # Generic comparison
-            return RingMap._richcmp_(self, other, op)
-        # Two coercion maps with the same parent must be equal
-        return rich_to_bool(op, 0)
-
-    def __hash__(self):
-        """
-        Return the hash of this morphism.
-
-        TESTS::
-
-            sage: from sage.rings.morphism import RingHomomorphism_coercion
-            sage: parent = Hom(ZZ,ZZ)
-            sage: f = parent.__make_element_class__(RingHomomorphism_coercion)(parent)
-            sage: g = parent.__make_element_class__(RingHomomorphism_coercion)(parent)
-            sage: hash(f) == hash(g)
-            True
-
-        """
-        return hash((self.domain(), self.codomain()))
-
-    cpdef Element _call_(self, x):
-        """
-        Evaluate this coercion morphism at ``x``.
-
-        EXAMPLES::
-
-            sage: from sage.rings.morphism import RingHomomorphism_coercion
-            sage: parent = Hom(ZZ,ZZ)
-            sage: f = parent.__make_element_class__(RingHomomorphism_coercion)(parent)
-            sage: f(0)
-            0
-
-        """
-        return self.codomain().coerce(x)
-
-
 cdef class RingHomomorphism_im_gens(RingHomomorphism):
     """
     A ring homomorphism determined by the images of generators.