Make Nuclide, Element, and Macroscopic subclasses of str

openmc/element.py

@@ -10,7 +10,7 @@ import openmc.checkvalue as cv
 from openmc.data import NATURAL_ABUNDANCE, atomic_mass
 
 
-class Element(object):
+class Element(str):
     """A natural element that auto-expands to add the isotopes of an element to
     a material in their natural abundance. Internally, the OpenMC Python API
     expands the natural element into isotopes only when the materials.xml file
@@ -28,25 +28,14 @@ class Element(object):
 
     """
 
-    def __init__(self, name=''):
-        # Initialize class attributes
-        self._name = ''
-
-        # Set class attributes
-        self.name = name
-
-    def __repr__(self):
-        return 'Element    -    {0}\n'.format(self._name)
+    def __new__(cls, name):
+        cv.check_type('element name', name, string_types)
+        cv.check_length('element name', name, 1, 2)
+        return super(Element, cls).__new__(cls, name)
 
     @property
     def name(self):
-        return self._name
-
-    @name.setter
-    def name(self, name):
-        cv.check_type('element name', name, string_types)
-        cv.check_length('element name', name, 1, 2)
-        self._name = name
+        return self
 
     def expand(self, percent, percent_type, enrichment=None,
                cross_sections=None):
@@ -93,7 +82,7 @@ class Element(object):
         # Get the nuclides present in nature
         natural_nuclides = set()
         for nuclide in sorted(NATURAL_ABUNDANCE.keys()):
-            if re.match(r'{}\d+'.format(self.name), nuclide):
+            if re.match(r'{}\d+'.format(self), nuclide):
                 natural_nuclides.add(nuclide)
 
         # Create dict to store the expanded nuclides and abundances
@@ -113,7 +102,7 @@ class Element(object):
             root = tree.getroot()
             for child in root:
                 nuclide = child.attrib['materials']
-                if re.match(r'{}\d+'.format(self.name), nuclide) and \
+                if re.match(r'{}\d+'.format(self), nuclide) and \
                    '_m' not in nuclide:
                     library_nuclides.add(nuclide)
 
@@ -134,14 +123,14 @@ class Element(object):
             # 0 nuclide is present. If so, set the abundance to 1 for this
             # nuclide. Else, raise an error.
             elif len(mutual_nuclides) == 0:
-                nuclide_0 = self.name + '0'
+                nuclide_0 = self + '0'
                 if nuclide_0 in library_nuclides:
                     abundances[nuclide_0] = 1.0
                 else:
                     msg = 'Unable to expand element {0} because the cross '\
                           'section library provided does not contain any of '\
                           'the natural isotopes for that element.'\
-                          .format(self.name)
+                          .format(self)
                     raise ValueError(msg)
 
             # If some, but not all, natural nuclides are in the library, add

openmc/macroscopic.py

@@ -3,7 +3,7 @@ from six import string_types
 from openmc.checkvalue import check_type
 
 
-class Macroscopic(object):
+class Macroscopic(str):
     """A Macroscopic object that can be used in a material.
 
     Parameters
@@ -18,22 +18,10 @@ class Macroscopic(object):
 
     """
 
-    def __init__(self, name=''):
-        # Initialize class attributes
-        self._name = ''
-
-        # Set the Macroscopic class attributes
-        self.name = name
-
-    def __repr__(self):
-        string = 'Macroscopic    -    {0}\n'.format(self._name)
-        return string
+    def __new__(cls, name):
+        check_type('name', name, string_types)
+        return super(Macroscopic, cls).__new__(cls, name)
 
     @property
     def name(self):
-        return self._name
-
-    @name.setter
-    def name(self, name):
-        check_type('name', name, string_types)
-        self._name = name
+        return self

openmc/nuclide.py

@@ -5,7 +5,7 @@ from six import string_types
 import openmc.checkvalue as cv
 
 
-class Nuclide(object):
+class Nuclide(str):
     """A nuclide that can be used in a material.
 
     Parameters
@@ -20,54 +20,22 @@ class Nuclide(object):
 
     """
 
-    def __init__(self, name=''):
+    def __new__(cls, name):
         # Initialize class attributes
-        self._name = ''
+        orig_name = name
 
-        # Set the Material class attributes
-        self.name = name
+        if '-' in name:
+            name = name.replace('-', '')
+            name = name.replace('Nat', '0')
+            if name.endswith('m'):
+                name = name[:-1] + '_m1'
 
-    def __eq__(self, other):
-        if isinstance(other, Nuclide):
-            if self.name != other.name:
-                return False
-            else:
-                return True
-        elif isinstance(other, string_types) and other == self.name:
-            return True
-        else:
-            return False
+            msg = 'OpenMC nuclides follow the GND naming convention. Nuclide ' \
+                  '"{}" is being renamed as "{}".'.format(orig_name, name)
+            warnings.warn(msg)
 
-    def __ne__(self, other):
-        return not self == other
-
-    def __gt__(self, other):
-        return repr(self) > repr(other)
-
-    def __lt__(self, other):
-        return not self > other
-
-    def __hash__(self):
-        return hash(repr(self))
-
-    def __repr__(self):
-        return 'Nuclide    -    {0}\n'.format(self._name)
+        return super(Nuclide, cls).__new__(cls, name)
 
     @property
     def name(self):
-        return self._name
-
-    @name.setter
-    def name(self, name):
-        cv.check_type('name', name, string_types)
-        self._name = name
-
-        if '-' in name:
-            self._name = name.replace('-', '')
-            self._name = self._name.replace('Nat', '0')
-            if self._name.endswith('m'):
-                self._name = self._name[:-1] + '_m1'
-
-            msg = 'OpenMC nuclides follow the GND naming convention. Nuclide ' \
-                  '"{}" is being renamed as "{}".'.format(name, self._name)
-            warnings.warn(msg)
+        return self