'FunctionSpace' object has no attribute 'super'

Errors
1

Hello,

I am having trouble with a fairly simple task. I want to create a Function based of a mixed element space.
I found a few examples for that, but for some reason all of them result in the same error and I can’t see where I made a mistake. Below is the code that produces the error

import numpy as np
from ufl import *
import dolfinx
from dolfinx import mesh, fem, io, plot
from dolfinx.fem.petsc import LinearProblem
from dolfinx.nls.petsc import NewtonSolver
from mpi4py import MPI
from petsc4py import PETSc

domain = mesh.create_rectangle(MPI.COMM_WORLD, [(0.0, 0.0), (10.0, 1.0)],
                          (50,5), mesh.CellType.quadrilateral)
U = VectorElement("Lagrange", domain.ufl_cell(), degree=2)
P = FiniteElement("Lagrange", domain.ufl_cell(), degree=1)
space = FunctionSpace(domain, U*P)

w0 = fem.Function(space)

The error I get is

AttributeError                            Traceback (most recent call last)
/home/vm/fenics/up-fenicsx.ipynb Cell 2 line 1
     13 P = FiniteElement("Lagrange", domain.ufl_cell(), degree=1)
     14 space = FunctionSpace(domain, U*P)
---> 16 w0 = fem.Function(space)

File ~/anaconda3/envs/fenicsx/lib/python3.11/site-packages/dolfinx/fem/function.py:302, in Function.__init__(self, V, x, name, dtype)
    300     self._cpp_object = functiontype(dtype)(V._cpp_object, x._cpp_object)
    301 else:
--> 302     self._cpp_object = functiontype(dtype)(V._cpp_object)
    304 # Initialize the ufl.FunctionSpace
    305 super().__init__(V.ufl_function_space())

AttributeError: 'FunctionSpace' object has no attribute '_cpp_object'

w0 is supposed to store the initial condition for my problem, if that helps. Not sure if this note helps, but I can create Testfunctions and a Trialfunction from space.

2

If you are using current main branch, the creation of a function space now happens with functionspace rather than FunctionSpace. If you are not using main, please add more details on how you installed dolfinx.

3

I’ll leave the answer there in case other people come to this topic in future, but after reading again the code I suspect that the issue is different.

You are using FunctionSpace from ufl. Instead you should be using functionspace (preferred non-deprecated way, if available) or FunctionSpace from dolfinx.fem (or fem, since you imported it from dolfinx).

4

Changing FunctionSpace to functionspace actually did the trick.
Thank you.