cleanup of write_to_csv in MeasurementResult (fixes #30) Leaking file handle when exception occurs during write

src/damaris/data/MeasurementResult.py

@@ -1,6 +1,5 @@
 import threading
 import math
-import types
 import sys
 import tables
 import numpy
@@ -45,7 +44,7 @@ class AccumulatedValue:
 
     def __add__(self,y):
         new_one=AccumulatedValue()
-        if (type(y) is types.InstanceType and isinstance(y, AccumulatedValue)):
+        if isinstance(y, AccumulatedValue):
             new_one.y=self.y+y.y
             new_one.y2=self.y2+y.y2
             new_one.n=self.n+y.n
@@ -56,7 +55,7 @@ class AccumulatedValue:
         return new_one
 
     def __iadd__(self,y):
-        if (type(y) is types.InstanceType and isinstance(y, AccumulatedValue)):
+        if isinstance(y, AccumulatedValue):
             self.y+=y.y
             self.y2+=y.y2
             self.n+=y.n
@@ -203,28 +202,27 @@ class MeasurementResult(Drawable.Drawable, collections.UserDict):
         destination can be a file or a filename
         suitable for further processing
         """
-        the_destination=destination
-        file_opened = False
-        if type(destination) in (str,):
-            the_destination=open(destination, "w")
-            file_opened = True
+        if isinstance(destination, str):
+            with open(destination, "w") as f:
+                self._write_to_csv_dest(f, delimiter)
+        else:
+            self._write_to_csv_dest(destination, delimiter)
 
-        the_destination.write("# quantity:"+str(self.quantity_name)+"\n")
-        the_destination.write("# x y ysigma n\n")
+    def _write_to_csv_dest(self, dest, delimiter):
+        dest.write("# quantity:"+str(self.quantity_name)+"\n")
+        dest.write("# x y ysigma n\n")
         for x in self.get_xdata():
-            y=self.data[x]
-            if type(y) in [float, int, int]:
-                the_destination.write("%e%s%e%s0%s1\n"%(x, delimiter, y, delimiter, delimiter))
+            y = self.data[x]
+            if isinstance(y, (float, int)):
+                dest.write("%e%s%e%s0%s1\n" % (x, delimiter, y, delimiter, delimiter))
             else:
-                the_destination.write("%e%s%e%s%e%s%d\n"%(x,
-                                                          delimiter,
-                                                          y.mean(),
-                                                          delimiter,
-                                                          y.mean_error(),
-                                                          delimiter,
-                                                          y.n))
-        if file_opened:
-            the_destination.close()
+                dest.write("%e%s%e%s%e%s%d\n" % (x,
+                                                 delimiter,
+                                                 y.mean(),
+                                                 delimiter,
+                                                 y.mean_error(),
+                                                 delimiter,
+                                                 y.n))
 
 
     def write_to_hdf(self, hdffile, where, name, title, complib=None, complevel=None):