add CountEmitter and test

saucebrush/emitters.py

@@ -53,6 +53,34 @@ class DebugEmitter(Emitter):
         self._outfile.write(str(record) + '\n')
 
 
+class CountEmitter(Emitter):
+    """ Emitter that writes the record count to a file-like object.
+    
+        CountEmitter() by default writes to stdout.
+        CountEmitter(outfile=open('text', 'w')) would print to a file name test.
+        CountEmitter(every=1000000) would write the count every 1,000,000 records.
+    """
+
+    def __init__(self, every=1000, outfile=None, format=None):
+        super(CountEmitter, self).__init__()
+        if not outfile:
+            import sys
+            self._outfile = sys.stdout
+        else:
+            self._outfile = outfile
+        self._format = "%s\n" if format is None else format
+        self._every = every
+        self.count = 0
+
+    def emit_record(self, record):
+        self.count += 1
+        if self.count % self._every == 0:
+            self._outfile.write(self._format % self.count)
+    
+    def done(self):
+        self._outfile.write(self._format % self.count)
+
+
 class CSVEmitter(Emitter):
     """ Emitter that writes records to a CSV file.
 

saucebrush/tests/emitters.py

@@ -1,6 +1,6 @@
 import unittest
 from cStringIO import StringIO
-from saucebrush.emitters import DebugEmitter, CSVEmitter
+from saucebrush.emitters import DebugEmitter, CSVEmitter, CountEmitter
 
 class EmitterTestCase(unittest.TestCase):
 
@@ -21,5 +21,14 @@ class EmitterTestCase(unittest.TestCase):
             pass
         self.assertEquals(self.output.getvalue(), 'x,y,z\r\n1,2,3\r\n5,5,5\r\n')
     
+    def test_count_emitter(self):
+        ce = CountEmitter(every=10, outfile=self.output, format="%s records\n")
+        data = ce.attach([1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22])
+        for _ in data:
+            pass
+        self.assertEquals(self.output.getvalue(), '10 records\n20 records\n')
+        ce.done()
+        self.assertEquals(self.output.getvalue(), '10 records\n20 records\n22 records\n')
+
 if __name__ == '__main__':
     unittest.main()