for a in "CLASS='LinearFunction';SUFFIX=" ; do eval "$a"; git --no-pager grep -l -E 'is_('$CLASS')' src/sage | xargs sed -E -i.bak 's/import is_('$CLASS')/import \1'$SUFFIX'/;/^ +/s/is_('$CLASS')[(]([^()]*([(][^()]*[)])?[^()]*)[)]/isinstance(\2, \1'$SUFFIX')/g'; done

Author: Matthias Koeppe

src/sage/numerical/linear_functions.pyx

@@ -690,7 +690,7 @@ cdef class LinearFunctionsParent_class(Parent):
             sage: LF_QQ(f) is f
             False
         """
-        if is_LinearFunction(x):
+        if isinstance(x, LinearFunction):
             return LinearFunction(self, (<LinearFunction>x)._f)
         return LinearFunction(self, x)
 
@@ -891,7 +891,7 @@ cdef class LinearFunction(LinearFunctionOrConstraint):
             ...
             ValueError: x is from a different linear functions module
         """
-        if is_LinearFunction(x):
+        if isinstance(x, LinearFunction):
             if self.parent() != x.parent():
                 raise ValueError('x is from a different linear functions module')
             if len((<LinearFunction>x)._f) != 1:

src/sage/numerical/linear_tensor.py

@@ -99,7 +99,7 @@
 
 from sage.structure.parent import Parent
 from sage.misc.cachefunc import cached_function
-from sage.numerical.linear_functions import is_LinearFunction, LinearFunctionsParent_class
+from sage.numerical.linear_functions import LinearFunction, LinearFunctionsParent_class
 from sage.numerical.linear_tensor_element import LinearTensor
 
 
@@ -415,7 +415,7 @@ def _element_constructor_(self, x):
         M = self.free_module()
         if isinstance(x, LinearTensor):
             x = x.dict()
-        elif is_LinearFunction(x):
+        elif isinstance(x, LinearFunction):
             x = dict([key, self._convert_constant(value)] for key, value in x.dict().items())
         elif isinstance(x, dict):
             x = dict([int(key), M(value)] for key, value in x.items())

src/sage/numerical/linear_tensor_element.pyx

@@ -169,7 +169,7 @@ cdef class LinearTensor(ModuleElement):
             ...
             ValueError: x is from a different linear functions module
         """
-        if is_LinearFunction(x):
+        if isinstance(x, LinearFunction):
             if self.parent().linear_functions() != x.parent():
                 raise ValueError('x is from a different linear functions module')
             if len((<LinearFunction>x)._f) != 1:

src/sage/numerical/mip.pyx

@@ -2134,12 +2134,12 @@ cdef class MixedIntegerLinearProgram(SageObject):
             sage: p.solve()
             6.0
         """
-        from sage.numerical.linear_functions import is_LinearFunction, is_LinearConstraint
+        from sage.numerical.linear_functions import LinearFunction, LinearConstraint
         from sage.numerical.linear_tensor import LinearTensor
         from sage.numerical.linear_tensor_constraints import LinearTensorConstraint
-        if is_LinearFunction(linear_function) or isinstance(linear_function, LinearTensor):
+        if isinstance(linear_function, LinearFunction) or isinstance(linear_function, LinearTensor):
             # Find the parent for the coefficients
-            if is_LinearFunction(linear_function):
+            if isinstance(linear_function, LinearFunction):
                 M = linear_function.parent().base_ring()
             elif isinstance(linear_function, LinearTensor):
                 if not linear_function.parent().is_vector_space():
@@ -2164,7 +2164,7 @@ cdef class MixedIntegerLinearProgram(SageObject):
             except KeyError:
                 pass
             # Send to backend
-            if is_LinearFunction(linear_function):
+            if isinstance(linear_function, LinearFunction):
                 if self._check_redundant and self._is_redundant_constraint(constraint, min, max):
                     if return_indices:
                         return []

src/sage/numerical/sdp.pyx

@@ -233,7 +233,7 @@ AUTHORS:
 
 from sage.structure.parent cimport Parent
 from sage.structure.element cimport Element
-from sage.numerical.linear_functions import is_LinearFunction, is_LinearConstraint
+from sage.numerical.linear_functions import LinearFunction, LinearConstraint
 from sage.matrix.constructor import matrix
 from sage.structure.element import Matrix
 
@@ -906,7 +906,7 @@ cdef class SemidefiniteProgram(SageObject):
             else:
                 self.add_constraint(c.lhs()-c.rhs(), name=name)
 
-        elif is_LinearFunction(linear_function) or isinstance(linear_function, LinearTensor):
+        elif isinstance(linear_function, LinearFunction) or isinstance(linear_function, LinearTensor):
             l = sorted(linear_function.dict().items())
             self._backend.add_linear_constraint(l, name)