Remove RingHomomorphism_coercion

In the places where this was still used, _call_ was overriden, so the only
thing that we need to take care of are the comparison operators. Running the
TestSuite for all of them should make sure that we catch all the equalities
that need to be replaced (otherwise pickling fails.)

Author: saraedum

src/sage/rings/fraction_field_FpT.pxd

@@ -1,6 +1,6 @@
 from sage.libs.flint.types cimport nmod_poly_t
 
-from sage.rings.morphism cimport RingHomomorphism_coercion
+from sage.rings.morphism cimport RingHomomorphism
 from sage.categories.morphism cimport Morphism
 from sage.structure.element cimport Element, ModuleElement, RingElement
 from sage.categories.map cimport Section

src/sage/rings/fraction_field_FpT.pyx

@@ -996,7 +996,7 @@ cdef class FpT_iter:
             self.cur = next_
         return self.cur
 
-cdef class Polyring_FpT_coerce(RingHomomorphism_coercion):
+cdef class Polyring_FpT_coerce(RingHomomorphism):
     """
     This class represents the coercion map from GF(p)[t] to GF(p)(t)
 
@@ -1010,6 +1010,11 @@ cdef class Polyring_FpT_coerce(RingHomomorphism_coercion):
           To:   Fraction Field of Univariate Polynomial Ring in t over Finite Field of size 5
         sage: type(f)
         <type 'sage.rings.fraction_field_FpT.Polyring_FpT_coerce'>
+
+    TESTS::
+
+        TestSuite(f).run()
+
     """
     cdef long p
 
@@ -1024,7 +1029,7 @@ cdef class Polyring_FpT_coerce(RingHomomorphism_coercion):
             sage: R.<t> = GF(next_prime(2000))[]
             sage: K = R.fraction_field() # indirect doctest
         """
-        RingHomomorphism_coercion.__init__(self, R.ring_of_integers().Hom(R), check=False)
+        RingHomomorphism.__init__(self, R.ring_of_integers().Hom(R))
         self.p = R.base_ring().characteristic()
 
     cdef dict _extra_slots(self, dict _slots):
@@ -1040,7 +1045,7 @@ cdef class Polyring_FpT_coerce(RingHomomorphism_coercion):
             t^2 + 1
         """
         _slots['p'] = self.p
-        return RingHomomorphism_coercion._extra_slots(self, _slots)
+        return RingHomomorphism._extra_slots(self, _slots)
 
     cdef _update_slots(self, dict _slots):
         """
@@ -1055,7 +1060,7 @@ cdef class Polyring_FpT_coerce(RingHomomorphism_coercion):
             t^2 + 1
         """
         self.p = _slots['p']
-        RingHomomorphism_coercion._update_slots(self, _slots)
+        RingHomomorphism._update_slots(self, _slots)
 
     cpdef Element _call_(self, _x):
         """
@@ -1193,6 +1198,11 @@ cdef class FpT_Polyring_section(Section):
           To:   Univariate Polynomial Ring in t over Finite Field of size 5
         sage: type(f)
         <type 'sage.rings.fraction_field_FpT.FpT_Polyring_section'>
+
+    TESTS::
+
+        sage: TestSuite(f).run()
+
     """
     cdef long p
 
@@ -1290,7 +1300,7 @@ cdef class FpT_Polyring_section(Section):
         ans._cparent = get_cparent(ans._parent)
         return ans
 
-cdef class Fp_FpT_coerce(RingHomomorphism_coercion):
+cdef class Fp_FpT_coerce(RingHomomorphism):
     """
     This class represents the coercion map from GF(p) to GF(p)(t)
 
@@ -1304,6 +1314,11 @@ cdef class Fp_FpT_coerce(RingHomomorphism_coercion):
           To:   Fraction Field of Univariate Polynomial Ring in t over Finite Field of size 5
         sage: type(f)
         <type 'sage.rings.fraction_field_FpT.Fp_FpT_coerce'>
+
+    TESTS::
+
+        sage: TestSuite(f).run()
+
     """
     cdef long p
 
@@ -1318,7 +1333,7 @@ cdef class Fp_FpT_coerce(RingHomomorphism_coercion):
             sage: R.<t> = GF(next_prime(3000))[]
             sage: K = R.fraction_field() # indirect doctest
         """
-        RingHomomorphism_coercion.__init__(self, R.base_ring().Hom(R), check=False)
+        RingHomomorphism.__init__(self, R.base_ring().Hom(R))
         self.p = R.base_ring().characteristic()
 
     cdef dict _extra_slots(self, dict _slots):
@@ -1337,7 +1352,7 @@ cdef class Fp_FpT_coerce(RingHomomorphism_coercion):
             True
         """
         _slots['p'] = self.p
-        return RingHomomorphism_coercion._extra_slots(self, _slots)
+        return RingHomomorphism._extra_slots(self, _slots)
 
     cdef _update_slots(self, dict _slots):
         """
@@ -1355,7 +1370,7 @@ cdef class Fp_FpT_coerce(RingHomomorphism_coercion):
             True
         """
         self.p = _slots['p']
-        RingHomomorphism_coercion._update_slots(self, _slots)
+        RingHomomorphism._update_slots(self, _slots)
 
     cpdef Element _call_(self, _x):
         """
@@ -1471,6 +1486,11 @@ cdef class FpT_Fp_section(Section):
           To:   Finite Field of size 5
         sage: type(f)
         <type 'sage.rings.fraction_field_FpT.FpT_Fp_section'>
+
+    TESTS::
+
+        sage: TestSuite(f).run()
+
     """
     cdef long p
 
@@ -1587,7 +1607,7 @@ cdef class FpT_Fp_section(Section):
         ans.ivalue = nmod_poly_get_coeff_ui(x._numer, 0)
         return ans
 
-cdef class ZZ_FpT_coerce(RingHomomorphism_coercion):
+cdef class ZZ_FpT_coerce(RingHomomorphism):
     """
     This class represents the coercion map from ZZ to GF(p)(t)
 
@@ -1601,6 +1621,11 @@ cdef class ZZ_FpT_coerce(RingHomomorphism_coercion):
           To:   Fraction Field of Univariate Polynomial Ring in t over Finite Field of size 17
         sage: type(f)
         <type 'sage.rings.fraction_field_FpT.ZZ_FpT_coerce'>
+
+    TESTS::
+
+        sage: TestSuite(f).run()
+
     """
     cdef long p
 
@@ -1615,7 +1640,7 @@ cdef class ZZ_FpT_coerce(RingHomomorphism_coercion):
             sage: R.<t> = GF(next_prime(3000))[]
             sage: K = R.fraction_field() # indirect doctest
         """
-        RingHomomorphism_coercion.__init__(self, ZZ.Hom(R), check=False)
+        RingHomomorphism.__init__(self, ZZ.Hom(R))
         self.p = R.base_ring().characteristic()
 
     cdef dict _extra_slots(self, dict _slots):
@@ -1636,7 +1661,7 @@ cdef class ZZ_FpT_coerce(RingHomomorphism_coercion):
             True
         """
         _slots['p'] = self.p
-        return RingHomomorphism_coercion._extra_slots(self, _slots)
+        return RingHomomorphism._extra_slots(self, _slots)
 
     cdef _update_slots(self, dict _slots):
         """
@@ -1656,7 +1681,7 @@ cdef class ZZ_FpT_coerce(RingHomomorphism_coercion):
             True
         """
         self.p = _slots['p']
-        RingHomomorphism_coercion._update_slots(self, _slots)
+        RingHomomorphism._update_slots(self, _slots)
 
     cpdef Element _call_(self, _x):
         """

src/sage/rings/morphism.pxd

@@ -17,9 +17,6 @@ cdef class RingMap_lift(RingMap):
 cdef class RingHomomorphism(RingMap):
     cdef RingMap _lift
 
-cdef class RingHomomorphism_coercion(RingHomomorphism):
-    pass
-
 cdef class RingHomomorphism_im_gens(RingHomomorphism):
     cdef __im_gens
 

src/sage/rings/morphism.pyx

@@ -901,107 +901,6 @@ cdef class RingHomomorphism(RingMap):
             return self._lift
         return self._lift(x)
 
-cdef class RingHomomorphism_coercion(RingHomomorphism):
-    def __init__(self, parent, check = True):
-        """
-        Initialize ``self``.
-
-        INPUT:
-
-        - ``parent`` -- ring homset
-
-        - ``check`` -- bool (default: ``True``)
-
-        EXAMPLES::
-
-            sage: f = ZZ.hom(QQ); f                    # indirect doctest
-            Natural morphism:
-              From: Integer Ring
-              To:   Rational Field
-
-            sage: f == loads(dumps(f))
-            True
-        """
-        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: f = ZZ.hom(QQ)
-            sage: type(f)
-            <type 'sage.rings.rational.Z_to_Q'>
-            sage: f._repr_type()
-            'Natural'
-        """
-        return "Ring Coercion"
-
-    def __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: f = ZZ.hom(QQ)
-            sage: g = ZZ.hom(ZZ)
-            sage: f == g
-            False
-
-            sage: h = Zmod(6).lift()
-            sage: f == h
-            False
-        """
-        if op not in [Py_EQ, Py_NE]:
-            return NotImplemented
-
-        if not isinstance(other, RingHomomorphism_coercion):
-            return (op == Py_NE)
-
-        # Since they are coercion morphisms they are determined by
-        # their parents, i.e., by the domain and codomain, so we just
-        # compare those.
-        return richcmp(self.parent(), other.parent(), op)
-
-    def __hash__(self):
-        """
-        Return the hash of this morphism.
-
-        TESTS::
-
-            sage: f = ZZ.hom(QQ)
-            sage: type(f)
-            <type 'sage.rings.rational.Z_to_Q'>
-            sage: hash(f) == hash(f)
-            True
-            sage: {f: 1}[f]
-            1
-        """
-        return hash((self.domain(), self.codomain()))
-
-    cpdef Element _call_(self, x):
-        """
-        Evaluate this coercion morphism at ``x``.
-
-        EXAMPLES::
-
-            sage: f = ZZ.hom(QQ); type(f)
-            <type 'sage.rings.rational.Z_to_Q'>
-            sage: f(2) == 2
-            True
-            sage: type(f(2))          # indirect doctest
-            <type 'sage.rings.rational.Rational'>
-        """
-        return self.codomain().coerce(x)
-
 import sage.structure.all
 
 cdef class RingHomomorphism_im_gens(RingHomomorphism):

src/sage/rings/padics/CA_template.pxi

@@ -1029,7 +1029,7 @@ cdef class CAElement(pAdicTemplateElement):
         """
         return chash(self.value, 0, self.absprec, self.prime_pow)
 
-cdef class pAdicCoercion_ZZ_CA(RingHomomorphism_coercion):
+cdef class pAdicCoercion_ZZ_CA(RingHomomorphism):
     """
     The canonical inclusion from the ring of integers to a capped absolute
     ring.
@@ -1040,6 +1040,11 @@ cdef class pAdicCoercion_ZZ_CA(RingHomomorphism_coercion):
         Ring Coercion morphism:
           From: Integer Ring
           To:   5-adic Ring with capped absolute precision 20
+
+    TESTS::
+
+        sage: TestSuite(f).run()
+
     """
     def __init__(self, R):
         """
@@ -1050,7 +1055,7 @@ cdef class pAdicCoercion_ZZ_CA(RingHomomorphism_coercion):
             sage: f = ZpCA(5).coerce_map_from(ZZ); type(f)
             <type 'sage.rings.padics.padic_capped_absolute_element.pAdicCoercion_ZZ_CA'>
         """
-        RingHomomorphism_coercion.__init__(self, ZZ.Hom(R), check=False)
+        RingHomomorphism.__init__(self, ZZ.Hom(R))
         self._zero = R._element_constructor(R, 0)
         self._section = pAdicConvert_CA_ZZ(R)
 
@@ -1071,7 +1076,7 @@ cdef class pAdicCoercion_ZZ_CA(RingHomomorphism_coercion):
         """
         _slots['_zero'] = self._zero
         _slots['_section'] = self._section
-        return RingHomomorphism_coercion._extra_slots(self, _slots)
+        return RingHomomorphism._extra_slots(self, _slots)
 
     cdef _update_slots(self, dict _slots):
         """
@@ -1090,7 +1095,7 @@ cdef class pAdicCoercion_ZZ_CA(RingHomomorphism_coercion):
         """
         self._zero = _slots['_zero']
         self._section = _slots['_section']
-        RingHomomorphism_coercion._update_slots(self, _slots)
+        RingHomomorphism._update_slots(self, _slots)
 
     cpdef Element _call_(self, x):
         """
@@ -1346,7 +1351,7 @@ cdef class pAdicConvert_QQ_CA(Morphism):
                 cconv_mpq_t(ans.value, (<Rational>x).value, ans.absprec, True, self._zero.prime_pow)
         return ans
 
-cdef class pAdicCoercion_CA_frac_field(RingHomomorphism_coercion):
+cdef class pAdicCoercion_CA_frac_field(RingHomomorphism):
     """
     The canonical inclusion of Zq into its fraction field.
 
@@ -1358,6 +1363,11 @@ cdef class pAdicCoercion_CA_frac_field(RingHomomorphism_coercion):
         Ring Coercion morphism:
           From: Unramified Extension of 3-adic Ring with capped absolute precision 20 in a defined by (1 + O(3^20))*x^3 + (O(3^20))*x^2 + (2 + O(3^20))*x + (1 + O(3^20))
           To:   Unramified Extension of 3-adic Field with capped relative precision 20 in a defined by (1 + O(3^20))*x^3 + (O(3^20))*x^2 + (2 + O(3^20))*x + (1 + O(3^20))
+
+    TESTS::
+
+        sage: TestSuite(f).run()
+
     """
     def __init__(self, R, K):
         """
@@ -1370,7 +1380,7 @@ cdef class pAdicCoercion_CA_frac_field(RingHomomorphism_coercion):
             sage: f = K.coerce_map_from(R); type(f)
             <type 'sage.rings.padics.qadic_flint_CA.pAdicCoercion_CA_frac_field'>
         """
-        RingHomomorphism_coercion.__init__(self, R.Hom(K), check=False)
+        RingHomomorphism.__init__(self, R.Hom(K))
         self._zero = K(0)
         self._section = pAdicConvert_CA_frac_field(K, R)
 
@@ -1485,7 +1495,7 @@ cdef class pAdicCoercion_CA_frac_field(RingHomomorphism_coercion):
         """
         _slots['_zero'] = self._zero
         _slots['_section'] = self._section
-        return RingHomomorphism_coercion._extra_slots(self, _slots)
+        return RingHomomorphism._extra_slots(self, _slots)
 
     cdef _update_slots(self, dict _slots):
         """
@@ -1513,7 +1523,7 @@ cdef class pAdicCoercion_CA_frac_field(RingHomomorphism_coercion):
         """
         self._zero = _slots['_zero']
         self._section = _slots['_section']
-        RingHomomorphism_coercion._update_slots(self, _slots)
+        RingHomomorphism._update_slots(self, _slots)
 
     def is_injective(self):
         r"""