BF: make a copy when addData() w/ mutables; closes psychopy#884

psychopy/data.py

@@ -222,6 +222,12 @@ def addData(self, name, value):
         """
         if name not in self.dataNames:
             self.dataNames.append(name)
+        # could just copy() every value, but not always needed, so check:
+        try:
+            hash(value)
+        except TypeError:
+            # unhashable type (list, dict, ...) == mutable, so need a copy()
+            value = copy.deepcopy(value)
         self.thisEntry[name]=value
 
     def nextEntry(self):

psychopy/tests/test_data/test_ExperimentHandler.py

@@ -76,6 +76,28 @@ def test_default(self):
         #    print e
         #print 'done'
 
+    def test_addData_with_mutable_values(self):
+        # add mutable objects to data, check that the value *at that time* is saved
+        exp = data.ExperimentHandler(
+            name='testExp',
+            savePickle=False,
+            saveWideText=True,
+            dataFileName=self.tmpDir + 'mutables'
+            )
+
+        mutant = [1]
+        exp.addData('mutable', mutant)
+        exp.nextEntry()
+        mutant[0] = 9999
+        exp.addData('mutable', mutant)
+        exp.nextEntry()
+
+        exp.saveAsWideText(exp.dataFileName+'.csv', delim=',')
+
+        #get data file contents:
+        contents = open(exp.dataFileName+'.csv', 'rU').read()
+        assert contents == "mutable,\n[1],\n[9999],\n"
+
     def test_unicode_conditions(self):
         fileName = self.tmpDir + 'unicode_conds'