some details in lean_matrix

Author: fchapoton

src/sage/matroids/lean_matrix.pyx

@@ -166,7 +166,7 @@ cdef class LeanMatrix:
         cdef long i, j
         cdef LeanMatrix A = type(self)(self.nrows(), self.ncols() + self.nrows())
         for i in range(self.nrows()):
-            A.set_unsafe(i, i, self.base_ring()(1))
+            A.set_unsafe(i, i, self.base_ring().one())
             for j in range(self.ncols()):
                 A.set_unsafe(i, self.nrows() + j, self.get_unsafe(i, j))
         return A
@@ -696,8 +696,8 @@ cdef class GenericMatrix(LeanMatrix):
         # Default:
         if self._base_ring is None:
             self._base_ring = ZZ
-        self._zero = self._base_ring(0)
-        self._one = self._base_ring(1)
+        self._zero = self._base_ring.zero()
+        self._one = self._base_ring.one()
         self._entries = [self._zero] * nrows * ncols
         if M is not None:
             if isinstance(M, GenericMatrix):
@@ -995,8 +995,8 @@ cdef class BinaryMatrix(LeanMatrix):
         global GF2, GF2_zero, GF2_one, GF2_not_defined
         if GF2_not_defined:
             GF2 = GF(2)
-            GF2_zero = GF2(0)
-            GF2_one = GF2(1)
+            GF2_zero = GF2.zero()
+            GF2_one = GF2.one()
             GF2_not_defined = False
         if M is not None:
             if isinstance(M, BinaryMatrix):
@@ -1433,7 +1433,7 @@ cdef class BinaryMatrix(LeanMatrix):
         if s_eq.nrows() != o_eq.nrows():
             return False
         if s_eq.nrows() == s_eq.ncols():  # s_eq and o_eq partition into singletons
-            morph = [0 for i in range(self._nrows)]
+            morph = [0 for _ in range(self._nrows)]
             for i in range(self._nrows):
                 morph[bitset_first(s_eq._M[i])] = bitset_first(o_eq._M[i])
             for i in range(self._nrows):
@@ -1580,8 +1580,8 @@ cdef class TernaryMatrix(LeanMatrix):
         global GF3, GF3_zero, GF3_one, GF3_minus_one, GF3_not_defined
         if GF3_not_defined:
             GF3 = GF(3)
-            GF3_zero = GF3(0)
-            GF3_one = GF3(1)
+            GF3_zero = GF3.zero()
+            GF3_one = GF3.one()
             GF3_minus_one = GF3(2)
             GF3_not_defined = False
 
@@ -2170,37 +2170,37 @@ cdef class QuaternaryMatrix(LeanMatrix):
         if M is not None:
             if isinstance(M, QuaternaryMatrix):
                 self._gf4 = (<QuaternaryMatrix>M)._gf4
-                self._zero = self._gf4(0)
-                self._one = self._gf4(1)
+                self._zero = self._gf4.zero()
+                self._one = self._gf4.one()
                 self._x_zero = self._gf4.gens()[0]
                 self._x_one = self._x_zero + self._one
                 for i in range((<QuaternaryMatrix>M)._nrows):
                     bitset_copy(self._M0[i], (<QuaternaryMatrix>M)._M0[i])
                     bitset_copy(self._M1[i], (<QuaternaryMatrix>M)._M1[i])
             elif isinstance(M, LeanMatrix):
                 self._gf4 = (<LeanMatrix>M).base_ring()
-                self._zero = self._gf4(0)
-                self._one = self._gf4(1)
+                self._zero = self._gf4.zero()
+                self._one = self._gf4.one()
                 self._x_zero = self._gf4.gens()[0]
                 self._x_one = self._x_zero + self._one
                 for i in range(M.nrows()):
                     for j in range(M.ncols()):
                         self.set(i, j, (<LeanMatrix>M).get_unsafe(i, j))
             elif isinstance(M, Matrix):
                 self._gf4 = (<Matrix>M).base_ring()
-                self._zero = self._gf4(0)
-                self._one = self._gf4(1)
+                self._zero = self._gf4.zero()
+                self._one = self._gf4.one()
                 self._x_zero = self._gf4.gens()[0]
                 self._x_one = self._x_zero + self._one
                 for i in range(M.nrows()):
                     for j in range(M.ncols()):
                         self.set(i, j, (<Matrix>M).get_unsafe(i, j))
             else:
-                raise TypeError("unrecognized input type.")
+                raise TypeError("unrecognized input type")
         else:
             self._gf4 = ring
-            self._zero = self._gf4(0)
-            self._one = self._gf4(1)
+            self._zero = self._gf4.zero()
+            self._one = self._gf4.one()
             self._x_zero = self._gf4.gens()[0]
             self._x_one = self._x_zero + self._one