fixing doctests, simplify coercion

sagemath · Feb 19, 2023 · bb38198 · bb38198
1 parent 8650c0c
commit bb38198
Showing 1 changed file with 21 additions and 87 deletions.
diff --git a/src/sage/rings/polynomial/integer_valued_polynomials.py b/src/sage/rings/polynomial/integer_valued_polynomials.py
@@ -483,7 +483,7 @@ def _element_constructor_(self, x):
                 return self.monomial(W(x))
 
             P = x.parent()
-            if isinstance(P, IntegerValuedPolynomialRing):
+            if isinstance(P, IntegerValuedPolynomialRing.Shifted):
                 if P is self:
                     return x
                 if P is not self.base_ring():
@@ -497,20 +497,21 @@ def _element_constructor_(self, x):
                 return self.element_class(self, {})
             return self.from_base_ring_from_one_basis(x)
 
-        def _coerce_impl(self, x):
+        def _coerce_map_from_(self, R):
             r"""
-            Canonical coercion of ``x`` into ``self``.
+            Return ``True`` if there is a coercion from ``R`` into ``self``
+            and ``False`` otherwise.
 
-            Here is what canonically coerces to ``self``:
+            INPUT:
 
-            - this integer-valued polynomial ring,
+            - ``R`` -- a commutative ring
+
+            The things that coerce into ``self`` are
 
-            - anything that coerces to the base ring of this
-              integer-valued polynomial ring,
+            - Integer-Valued Polynomial Rings over a base
+              with a coercion map into ``self.base_ring()``.
 
-            - any integer-valued polynomial ring,
-              whose base ring coerces to the base ring of this
-              integer-valued polynomial ring.
+            - Anything with a coercion into ``self.base_ring()``.
 
             EXAMPLES::
 
@@ -565,40 +566,6 @@ def _coerce_impl(self, x):
                 Ring over Finite Field of size 7  in the shifted basis
                 to Integer-Valued Polynomial
                 Ring over Integer Ring in the shifted basis
-            """
-            try:
-                R = x.parent()
-
-                # integer-valued polynomial rings
-                # over any base that coerces in:
-                if isinstance(R, IntegerValuedPolynomialRing):
-                    if self.has_coerce_map_from(R.base_ring()):
-                        return self(x)
-                    raise TypeError("no natural map between bases of"
-                                    " integer-valued polynomial rings")
-
-            except AttributeError:
-                pass
-
-            # any ring that coerces to the base ring of this integer-valued
-            # polynomial ring.
-            return self._coerce_try(x, [self.base_ring()])
-
-        def _coerce_map_from_(self, R):
-            r"""
-            Return ``True`` if there is a coercion from ``R`` into ``self``
-            and ``False`` otherwise.
-
-            INPUT:
-
-            - ``R`` -- a commutative ring
-
-            The things that coerce into ``self`` are
-
-            - Integer-Valued Polynomial Rings over a base
-              with a coercion map into ``self.base_ring()``.
-
-            - Anything with a coercion into ``self.base_ring()``.
 
             TESTS::
 
@@ -620,7 +587,7 @@ def _coerce_map_from_(self, R):
             """
             # integer-valued polynomial rings over any base
             # that coerces in:
-            if isinstance(R, IntegerValuedPolynomialRing):
+            if isinstance(R, IntegerValuedPolynomialRing.Shifted):
                 return self.base_ring().has_coerce_map_from(R.base_ring())
             return self.base_ring().has_coerce_map_from(R)
 
@@ -1035,7 +1002,7 @@ def _element_constructor_(self, x):
                 return self.monomial(W(x))
 
             P = x.parent()
-            if isinstance(P, IntegerValuedPolynomialRing):
+            if isinstance(P, IntegerValuedPolynomialRing.Binomial):
                 if P is self:
                     return x
                 if P is not self.base_ring():
@@ -1049,20 +1016,17 @@ def _element_constructor_(self, x):
                 return self.element_class(self, {})
             return self.from_base_ring_from_one_basis(x)
 
-        def _coerce_impl(self, x):
+        def _coerce_map_from_(self, R):
             r"""
-            Canonical coercion of ``x`` into ``self``.
-
-            Here is what canonically coerces to ``self``:
+            Return ``True`` if there is a coercion from ``R`` into ``self``
+            and ``False`` otherwise.
 
-            - this integer-valued polynomial ring,
+            The things that coerce into ``self`` are
 
-            - anything that coerces to the base ring of this
-              integer-valued polynomial ring,
+            - Integer-Valued Polynomial Rings over a base
+              with a coercion map into ``self.base_ring()``.
 
-            - any integer-valued polynomial ring,
-              whose base ring coerces to the base ring of this
-              integer-valued polynomial ring.
+            - Anything with a coercion into ``self.base_ring()``.
 
             EXAMPLES::
 
@@ -1117,36 +1081,6 @@ def _coerce_impl(self, x):
                 Ring over Finite Field of size 7 in the binomial basis to
                 Integer-Valued Polynomial Ring over Integer Ring
                 in the binomial basis
-            """
-            try:
-                R = x.parent()
-
-                # integer-valued polynomial rings
-                # over any base that coerces in:
-                if isinstance(R, IntegerValuedPolynomialRing):
-                    if self.has_coerce_map_from(R.base_ring()):
-                        return self(x)
-                    raise TypeError("no natural map between bases of"
-                                    " integer-valued polynomial rings")
-
-            except AttributeError:
-                pass
-
-            # any ring that coerces to the base ring of this integer-valued
-            # polynomial ring.
-            return self._coerce_try(x, [self.base_ring()])
-
-        def _coerce_map_from_(self, R):
-            r"""
-            Return ``True`` if there is a coercion from ``R`` into ``self``
-            and ``False`` otherwise.
-
-            The things that coerce into ``self`` are
-
-            - Integer-Valued Polynomial Rings over a base
-              with a coercion map into ``self.base_ring()``.
-
-            - Anything with a coercion into ``self.base_ring()``.
 
             TESTS::
 
@@ -1168,7 +1102,7 @@ def _coerce_map_from_(self, R):
             """
             # integer-valued polynomial rings over any base
             # that coerces in:
-            if isinstance(R, IntegerValuedPolynomialRing):
+            if isinstance(R, IntegerValuedPolynomialRing.Binomial):
                 return self.base_ring().has_coerce_map_from(R.base_ring())
             return self.base_ring().has_coerce_map_from(R)