implemented a separate generator class for object ID generation

* replaces the class variable based approach


git-svn-id: https://pycam.svn.sourceforge.net/svnroot/pycam/trunk@1240 bbaffbd6-741e-11dd-a85d-61de82d9cad9

src/pycam/Cutters/BaseCutter.py

@@ -22,6 +22,7 @@ along with PyCAM.  If not, see <http://www.gnu.org/licenses/>.
 """
 
 
+from pycam.Geometry import IDGenerator
 from pycam.Geometry.Point import Point
 from pycam.Geometry.utils import number, INFINITE, epsilon
 from pycam.Geometry.intersection import intersect_cylinder_point, \
@@ -29,19 +30,18 @@ from pycam.Geometry.intersection import intersect_cylinder_point, \
 import uuid
 
 
-class BaseCutter(object):
-    id = 0
+class BaseCutter(IDGenerator):
+
     vertical = Point(0, 0, -1)
 
     def __init__(self, radius, location=None, height=None):
+        super(BaseCutter, self).__init__()
         if location is None:
             location = Point(0, 0, 0)
         if height is None:
             height = 10
         radius = number(radius)
         self.height = number(height)
-        self.id = BaseCutter.id
-        BaseCutter.id += 1
         self.radius = radius
         self.radiussq = radius ** 2
         self.required_distance = 0

src/pycam/Geometry/__init__.py

@@ -184,6 +184,21 @@ def get_bezier_lines(points_with_bulge, segments=32):
         return result
 
 
+def _id_generator():
+    current_id = 0
+    while True:
+        yield current_id
+        current_id += 1
+
+
+class IDGenerator(object):
+
+    __id_gen_func = _id_generator()
+
+    def __init__(self):
+        self.id = self.__id_gen_func.next()
+
+
 class TransformableContainer(object):
     """ a base class for geometrical objects containing other elements