The difference between class and object variables

FourmiCrawler/sources/NIST.py

@@ -22,11 +22,11 @@ class NIST(Source):
 
     search = 'cgi/cbook.cgi?Name=%s&Units=SI&cTP=on'
 
-    ignore_list = set()
     cfg = {}
 
     def __init__(self, config={}):
         Source.__init__(self, config)
+        self.ignore_list = set()
         self.cfg = config
         if 'reliability' not in self.cfg or self.cfg['reliability'] == '':
             log.msg('Reliability not set for NIST', level=log.WARNING)

FourmiCrawler/spider.py

@@ -9,8 +9,6 @@ class FourmiSpider(Spider):
     A spider writen for the Fourmi Project which calls upon all available sources to request and scrape data.
     """
     name = "FourmiSpider"
-    _sources = []
-    synonyms = set()
 
     def __init__(self, compound=None, selected_attributes=[".*"], *args, **kwargs):
         """
@@ -18,6 +16,8 @@ class FourmiSpider(Spider):
         :param compound: compound that will be searched.
         :param selected_attributes: A list of regular expressions that the attributes should match.
         """
+        self._sources = []
+        self.synonyms = set()
         super(FourmiSpider, self).__init__(*args, **kwargs)
         self.synonyms.add(compound)
         self.selected_attributes = selected_attributes