Removed [] as parameter defaults

src/caosadvancedtools/table_importer.py

@@ -48,7 +48,8 @@ def yes_no_converter(val):
 
 
 class XLS_Importer(object):
-    def __init__(self, converters, obligatory_columns=[], unique_columns=[]):
+
+    def __init__(self, converters, obligatory_columns=None, unique_columns=None):
         """
 
         converters: dict with column names as keys and converter functions as
@@ -63,8 +64,8 @@ class XLS_Importer(object):
         """
         self.sup = Suppressable(logger=logger)
         self.required_columns = list(converters.keys())
-        self.obligatory_columns = obligatory_columns
-        self.unique_columns = unique_columns
+        self.obligatory_columns = [] if obligatory_columns is None else obligatory_columns
+        self.unique_columns = [] if unique_columns is None else unique_columns
         self.converters = converters
 
     def read_xls(self, filename):
@@ -72,10 +73,8 @@ class XLS_Importer(object):
 
         if len(xls_file .sheet_names) > 1:
             # Multiple sheets is the default now. Only show in debug
-            logger.debug("Excel file {} contains multiple sheets. "
-                         "All but the first are being ignored.".format(
-                             filename
-                         ))
+            logger.debug("Excel file %s contains multiple sheets. "
+                         "All but the first are being ignored.", filename)
 
         df = xls_file.parse(converters=self.converters)
         self.check_columns(df, filename=filename)