Reimplemented VantagePro logic and added test cases

* Complete re-write from last version
* Simplified serial data buffer parsing
* Added CRC checking of serial data
* Added DMPAFT command
* Added logging hooks

weather/services/wunderground.py

@@ -1,7 +1,4 @@
-from __future__ import absolute_import
-
-__doc__ = '''
-
+'''
 WUnderground.com Publisher
 
 Abstract:
@@ -42,6 +39,8 @@
 Date: 2006-03-27
 '''
 
+from __future__ import absolute_import
+
 import logging
 log = logging.getLogger(__name__)
 

weather/stations/_struct.py

@@ -0,0 +1,56 @@
+'''
+Binary Data Interfaces
+
+Abstract:
+Helper classes for working with binary data structures. This simplifies data
+field extraction from a binary buffer.
+
+Author: Patrick C. McGinty (pyweather@tuxcoder.com)
+Date: 2010-06-025
+'''
+
+from __future__ import absolute_import
+
+import struct
+
+
+class Struct( struct.Struct ):
+    '''
+    Implements a reusable class for working with a binary data structure. It
+    provides a named fields interface, similiar to C structures.
+
+    Usage: 1) subclass and extend _post_unpack method
+           2) instantiate directly, if no 'post unpack' processing needed
+
+    Arguments:
+        See `struct.Struct` class defintion.
+    '''
+    def __init__(self, fmt, order='@'):
+        self.fields, fmt_t = zip(*fmt)
+        super(Struct,self).__init__( order + ''.join(fmt_t) )
+
+
+    def unpack(self, buf):
+        '''
+        see unpack_from()
+        '''
+        return self.unpack_from( buf, offset=0 )
+
+
+    def unpack_from(self, buf, offset=0 ):
+        '''
+        unpacks data from 'buf' and returns a dication of named fields. the
+        fields can be post-processed by extending the _post_unpack() method.
+        '''
+        data = super(Struct,self).unpack_from( buf, offset)
+        items = dict(zip(self.fields,data))
+        return self._post_unpack(items)
+
+
+    def _post_unpack(self,items):
+        '''
+        perform data modification of any values, after unpacking from a buffer.
+        '''
+        return items
+
+# vim: sts=4:ts=4:sw=4