Use six.add_metaclass to be compatible with Python 2 and 3

openmc/data/angle_energy.py

@@ -1,14 +1,14 @@
 from abc import ABCMeta, abstractmethod
 
+from six import add_metaclass
+
 import openmc.data
 from openmc.mixin import EqualityMixin
 
 
+@add_metaclass(ABCMeta)
 class AngleEnergy(EqualityMixin):
     """Distribution in angle and energy of a secondary particle."""
-
-    __metaclass = ABCMeta
-
     @abstractmethod
     def to_hdf5(self, group):
         pass

openmc/data/energy_distribution.py

@@ -3,6 +3,7 @@ from collections import Iterable
 from numbers import Integral, Real
 from warnings import warn
 
+from six import add_metaclass
 import numpy as np
 
 from .function import Tabulated1D, INTERPOLATION_SCHEME
@@ -11,11 +12,9 @@ import openmc.checkvalue as cv
 from openmc.mixin import EqualityMixin
 
 
+@add_metaclass(ABCMeta)
 class EnergyDistribution(EqualityMixin):
     """Abstract superclass for all energy distributions."""
-
-    __metaclass__ = ABCMeta
-
     def __init__(self):
         pass
 

openmc/data/function.py

@@ -2,6 +2,7 @@ from abc import ABCMeta, abstractmethod
 from collections import Iterable, Callable
 from numbers import Real, Integral
 
+from six import add_metaclass
 import numpy as np
 
 import openmc.checkvalue as cv
@@ -11,11 +12,9 @@ INTERPOLATION_SCHEME = {1: 'histogram', 2: 'linear-linear', 3: 'linear-log',
                         4: 'log-linear', 5: 'log-log'}
 
 
+@add_metaclass(ABCMeta)
 class Function1D(EqualityMixin):
     """A function of one independent variable with HDF5 support."""
-
-    __metaclass__ = ABCMeta
-
     @abstractmethod
     def __call__(self): pass
 

openmc/filter.py

@@ -1,21 +1,17 @@
 from abc import ABCMeta, abstractproperty
 from collections import Iterable, OrderedDict
 import copy
-from six import with_metaclass
 from numbers import Real, Integral
 import sys
 from xml.etree import ElementTree as ET
 
+from six import add_metaclass
 import numpy as np
 
 import openmc
 import openmc.checkvalue as cv
 
 
-if sys.version_info[0] >= 3:
-    basestring = str
-
-
 _FILTER_TYPES = ['universe', 'material', 'cell', 'cellborn', 'surface',
                  'mesh', 'energy', 'energyout', 'mu', 'polar', 'azimuthal',
                  'distribcell', 'delayedgroup']
@@ -37,7 +33,8 @@ class FilterMeta(ABCMeta):
                                               **kwargs)
 
 
-class Filter(with_metaclass(FilterMeta, object)):
+@add_metaclass(FilterMeta)
+class Filter(object):
     """Tally modifier that describes phase-space and other characteristics.
 
     Parameters

openmc/lattice.py

@@ -7,6 +7,7 @@ from numbers import Real, Integral
 from xml.etree import ElementTree as ET
 import sys
 
+from six import ABCMeta
 import numpy as np
 
 import openmc.checkvalue as cv
@@ -16,6 +17,7 @@ if sys.version_info[0] >= 3:
     basestring = str
 
 
+@add_metaclass(ABCMeta)
 class Lattice(object):
     """A repeating structure wherein each element is a universe.
 
@@ -42,10 +44,6 @@ class Lattice(object):
         of the lattice
 
     """
-
-    # This is an abstract class which cannot be instantiated
-    __metaclass__ = abc.ABCMeta
-
     def __init__(self, lattice_id=None, name=''):
         # Initialize Lattice class attributes
         self.id = lattice_id

openmc/mgxs/mdgxs.py

@@ -8,6 +8,7 @@ import sys
 import copy
 import abc
 
+from six import ABCMeta
 import numpy as np
 
 import openmc
@@ -28,6 +29,7 @@ MDGXS_TYPES = ['delayed-nu-fission',
 MAX_DELAYED_GROUPS = 8
 
 
+@add_metaclass(ABCMeta)
 class MDGXS(MGXS):
     """An abstract multi-delayed-group cross section for some energy and delayed
     group structures within some spatial domain.
@@ -117,10 +119,6 @@ class MDGXS(MGXS):
         The key used to index multi-group cross sections in an HDF5 data store
 
     """
-
-    # This is an abstract class which cannot be instantiated
-    __metaclass__ = abc.ABCMeta
-
     def __init__(self, domain=None, domain_type=None, energy_groups=None,
                  delayed_groups=None, by_nuclide=False, name=''):
         super(MDGXS, self).__init__(domain, domain_type, energy_groups,

openmc/mgxs/mgxs.py

@@ -9,6 +9,7 @@ import copy
 import abc
 import itertools
 
+from six import add_metaclass
 import numpy as np
 
 import openmc
@@ -61,6 +62,7 @@ _DOMAINS = (openmc.Cell,
             openmc.Mesh)
 
 
+@add_metaclass(ABCMeta)
 class MGXS(object):
     """An abstract multi-group cross section for some energy group structure
     within some spatial domain.
@@ -145,10 +147,6 @@ class MGXS(object):
         The key used to index multi-group cross sections in an HDF5 data store
 
     """
-
-    # This is an abstract class which cannot be instantiated
-    __metaclass__ = abc.ABCMeta
-
     def __init__(self, domain=None, domain_type=None,
                  energy_groups=None, by_nuclide=False, name=''):
         self._name = ''
@@ -1530,7 +1528,7 @@ class MGXS(object):
 
         # Override energy groups bounds with indices
         all_groups = np.arange(self.num_groups, 0, -1, dtype=np.int)
-        all_groups = np.repeat(all_groups, len(query_nuclides)) 
+        all_groups = np.repeat(all_groups, len(query_nuclides))
         if 'energy low [MeV]' in df and 'energyout low [MeV]' in df:
             df.rename(columns={'energy low [MeV]': 'group in'},
                       inplace=True)
@@ -1616,6 +1614,7 @@ class MGXS(object):
         return 'cm^-1' if xs_type == 'macro' else 'barns'
 
 
+@add_metaclass(ABCMeta)
 class MatrixMGXS(MGXS):
     """An abstract multi-group cross section for some energy group structure
     within some spatial domain. This class is specifically intended for
@@ -1703,10 +1702,6 @@ class MatrixMGXS(MGXS):
         The key used to index multi-group cross sections in an HDF5 data store
 
     """
-
-    # This is an abstract class which cannot be instantiated
-    __metaclass__ = abc.ABCMeta
-
     @property
     def filters(self):
         # Create the non-domain specific Filters for the Tallies

openmc/model/triso.py

@@ -10,6 +10,7 @@ from heapq import heappush, heappop
 from math import pi, sin, cos, floor, log10, sqrt
 from abc import ABCMeta, abstractproperty, abstractmethod
 
+from six import add_metaclass
 import numpy as np
 try:
     import scipy.spatial
@@ -95,6 +96,7 @@ class TRISO(openmc.Cell):
                 k_min:k_max+1, j_min:j_max+1, i_min:i_max+1]))
 
 
+@add_metaclass(ABCMeta)
 class _Domain(object):
     """Container in which to pack particles.
 
@@ -123,9 +125,6 @@ class _Domain(object):
         Volume of the container.
 
     """
-
-    __metaclass__ = ABCMeta
-
     def __init__(self, particle_radius, center=[0., 0., 0.]):
         self._cell_length = None
         self._limits = None

openmc/region.py

@@ -1,11 +1,13 @@
 from abc import ABCMeta, abstractmethod
 from collections import Iterable
 
+from six import add_metaclass
 import numpy as np
 
 from openmc.checkvalue import check_type
 
 
+@add_metaclass(ABCMeta)
 class Region(object):
     """Region of space that can be assigned to a cell.
 
@@ -16,9 +18,6 @@ class Region(object):
     created through operators of the Surface and Region classes.
 
     """
-
-    __metaclass__ = ABCMeta
-
     def __and__(self, other):
         return Intersection(self, other)
 

openmc/stats/multivariate.py

@@ -5,6 +5,7 @@ from numbers import Real
 import sys
 from xml.etree import ElementTree as ET
 
+from six import add_metaclass
 import numpy as np
 
 import openmc.checkvalue as cv
@@ -14,6 +15,7 @@ if sys.version_info[0] >= 3:
     basestring = str
 
 
+@add_metaclass(ABCMeta)
 class UnitSphere(object):
     """Distribution of points on the unit sphere.
 
@@ -31,9 +33,6 @@ class UnitSphere(object):
         Direction from which polar angle is measured
 
     """
-
-    __metaclass__ = ABCMeta
-
     def __init__(self, reference_uvw=None):
         self._reference_uvw = None
         if reference_uvw is not None:
@@ -184,6 +183,7 @@ class Monodirectional(UnitSphere):
         return element
 
 
+@add_metaclass(ABCMeta)
 class Spatial(object):
     """Distribution of locations in three-dimensional Euclidean space.
 
@@ -191,9 +191,6 @@ class Spatial(object):
     distributions of source sites.
 
     """
-
-    __metaclass__ = ABCMeta
-
     def __init__(self):
         pass
 

openmc/stats/univariate.py

@@ -4,6 +4,7 @@ from numbers import Real
 import sys
 from xml.etree import ElementTree as ET
 
+from six import add_metaclass
 import numpy as np
 
 import openmc.checkvalue as cv
@@ -16,6 +17,7 @@ _INTERPOLATION_SCHEMES = ['histogram', 'linear-linear', 'linear-log',
                           'log-linear', 'log-log']
 
 
+@add_metaclass(ABCMeta)
 class Univariate(EqualityMixin):
     """Probability distribution of a single random variable.
 
@@ -23,9 +25,6 @@ class Univariate(EqualityMixin):
     specific probability distribution.
 
     """
-
-    __metaclass__ = ABCMeta
-
     def __init__(self):
         pass
 

openmc/surface.py

@@ -4,6 +4,7 @@ from xml.etree import ElementTree as ET
 import sys
 from math import sqrt
 
+from six import add_metaclass
 import numpy as np
 
 from openmc.checkvalue import check_type, check_value, check_greater_than
@@ -642,6 +643,7 @@ class ZPlane(Plane):
         return point[2] - self.z0
 
 
+@add_metaclass(ABCMeta)
 class Cylinder(Surface):
     """A cylinder whose length is parallel to the x-, y-, or z-axis.
 
@@ -677,9 +679,6 @@ class Cylinder(Surface):
         Type of the surface
 
     """
-
-    __metaclass__ = ABCMeta
-
     def __init__(self, surface_id=None, boundary_type='transmission',
                  R=1., name=''):
         super(Cylinder, self).__init__(surface_id, boundary_type, name=name)
@@ -1210,7 +1209,7 @@ class Sphere(Surface):
         z = point[2] - self.z0
         return x**2 + y**2 + z**2 - self.r**2
 
-
+@add_metaclass(ABCMeta)
 class Cone(Surface):
     """A conical surface parallel to the x-, y-, or z-axis.
 
@@ -1257,9 +1256,6 @@ class Cone(Surface):
         Type of the surface
 
     """
-
-    __metaclass__ = ABCMeta
-
     def __init__(self, surface_id=None, boundary_type='transmission',
                  x0=0., y0=0., z0=0., R2=1., name=''):
         super(Cone, self).__init__(surface_id, boundary_type, name=name)