Better implemenation of datasheet iterator.

Convert-EUProcessingFactorsDB/mcra.py

@@ -365,15 +365,7 @@ class DataSet:
     # It is usefull to be able to iterate over all the datasheets.
     # Basically, avoid using .list. in all DataSet references.
     def __iter__(self):
-        self.n = 0
-        return self
-
-    def __next__(self):
-        if self.n < len(self.list):
-            self.n = self.n + 1
-            return getattr(self, self.list[self.n-1])
-        else:
-            raise StopIteration
+        return iter(self.list)
 
     # Container for all the files
     def add(self, name, default_name, default_dir, short_argument=None,
@@ -381,6 +373,7 @@ class DataSet:
             necessary=True):
         if getattr(self, name, None) is None:
             # Create a new sheet with a different name
+            # directly under this class. Then no .list is needed
             setattr(self,
                     name,
                     DataSheet(
@@ -391,7 +384,7 @@ class DataSet:
                         direction=direction,
                         checksum=checksum,
                         autoload=autoload))
-
+            # But we must do some bookkeeping
             self.list.append(name)
 
             long_argument = '--'+name+'_file'