Merge pull request #43 from rtzoeller/attribute_assignment

Support keyword argument initialization of Structures

Author: posborne

suitcase/structure.py

@@ -242,6 +242,26 @@ class Structure(object):
           data=...'Hello, world!',
         )
 
+    Initialization via keyword argument is also supported::
+
+        >>> dgram = UDPDatagram(source_port=9110,
+        ...                     destination_port=1001,
+        ...                     checksum=27193,
+        ...                     data=b"Hello, world!")
+        ...
+        >>> printb(dgram.pack())
+        '#\x96\x03\xe9\x00\rj9Hello, world!'
+        >>> dgram2 = UDPDatagram()
+        >>> dgram2.unpack(dgram.pack())
+        >>> dgram2
+        UDPDatagram (
+          source_port=9110,
+          destination_port=1001,
+          length=13,
+          checksum=27193,
+          data=...'Hello, world!',
+        )
+
     """
 
     @classmethod
@@ -263,7 +283,7 @@ def from_data(cls, data):
         m.unpack(data)
         return m
 
-    def __init__(self):
+    def __init__(self, **kwargs):
         self._key_to_field = {}
         self._parent = None
         self._sorted_fields = []
@@ -278,6 +298,8 @@ def __init__(self):
             self._placeholder_to_field[field_placeholder] = field
             self._sorted_fields.append((key, field))
         self._packer = Packer(self._sorted_fields, self._crc_field)
+        for key, value in kwargs.items():
+            setattr(self, key, value)
 
     def __getattr__(self, key):
         k2f = self.__dict__.get('_key_to_field', {})

suitcase/test/test_fields.py

@@ -1198,5 +1198,21 @@ def test_dir(self):
         self.assertTrue("value" in attrs)
 
 
+class TestKeywordArgumentInitialization(unittest.TestCase):
+    def test_basic_assignment(self):
+        m = PascalString16(value=b"Hello World!")
+        self.assertEqual(m.pack(), b"\x00\x0cHello World!")
+
+    def test_nested_assignment(self):
+        m = NameStructure(first=PascalString16(value=b"John"),
+                          last=PascalString16(value=b"Doe"))
+        self.assertEqual(m.pack(), b"\x00\x04John\x00\x03Doe")
+
+    def test_partial_assignment(self):
+        m = NameStructure(first=PascalString16(value=b"John"))
+        m.last = PascalString16(value=b"Doe")
+        self.assertEqual(m.pack(), b"\x00\x04John\x00\x03Doe")
+
+
 if __name__ == "__main__":
     unittest.main()