Initial commit

Solutions/8_4/follow.py

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+# follow.py
+import os
+import time
+
+def follow(filename):
+    '''
+    Generator that produces a sequence of lines being written at the end of a file.
+    '''
+    try:
+        with open(filename,'r') as f:
+            f.seek(0,os.SEEK_END)
+            while True:
+                 line = f.readline()
+                 if line == '':
+                     time.sleep(0.1)    # Sleep briefly to avoid busy wait
+                     continue
+                 yield line
+    except GeneratorExit:
+        print('Following Done')
+
+def splitter(lines):
+    for line in lines:
+        yield line.split(',')
+
+
+def make_records(rows,names):
+    for row in rows:
+        yield dict(zip(names,row))
+
+def unquote(records,keylist):
+    for r in records:
+        for key in keylist:
+            r[key] = r[key].strip('"')
+        yield r
+
+def convert(records,converter,keylist):
+    for r in records:
+        for key in keylist:
+            r[key] = converter(r[key])
+        yield r
+
+def parse_stock_data(lines):
+    rows = splitter(lines)
+    records = make_records(rows,['name','price','date','time',
+                              'change','open','high','low','volume'])
+    records = unquote(records,["name","date","time"])
+    records = convert(records,float,['price','change','open','high','low'])
+    records = convert(records,int,['volume'])
+    return records
+
+# Sample use
+if __name__ == '__main__':
+   lines = follow("../../Data/stocklog.dat")
+   records = parse_stock_data(lines)
+   for r in records:
+       print("%(name)10s %(price)10.2f %(change)10.2f" % r)