Drafting suggested edits for #351.

keyring/__init__.py

@@ -1,9 +1,9 @@
 from __future__ import absolute_import
 
 from .core import (set_keyring, get_keyring, set_password, get_password,
-                   delete_password, get_username_and_password)
+                   delete_password, get_credential)
 
 __all__ = (
     'set_keyring', 'get_keyring', 'set_password', 'get_password',
-    'delete_password', 'get_username_and_password',
+    'delete_password', 'get_credential',
 )

keyring/backend.py

@@ -11,6 +11,7 @@
 import entrypoints
 
 from . import errors, util
+from . import credentials
 from .util import properties
 from .py27compat import add_metaclass, filter
 
@@ -109,11 +110,11 @@ def delete_password(self, service, username):
         raise errors.PasswordDeleteError("reason")
 
     # for backward-compatibility, don't require a backend to implement
-    #  get_username_and_password
+    #  get_credential
     # @abc.abstractmethod
-    def get_username_and_password(self, service, username):
+    def get_credential(self, service, username):
         """Gets the username and password for the service.
-        Returns (username, password)
+        Returns a Credential or None
 
         The *username* argument is optional and may be omitted by
         the caller or ignored by the backend. Callers must use the
@@ -123,8 +124,7 @@ def get_username_and_password(self, service, username):
         if username is not None:
             password = self.get_password(service, username)
             if password is not None:
-                return username, password
-        return None, None
+                return credentials.SimpleCredential(username, password)
 
 
 class Crypter:

keyring/backends/Windows.py

@@ -6,6 +6,7 @@
 from ..util import properties
 from ..backend import KeyringBackend
 from ..errors import PasswordDeleteError, ExceptionRaisedContext
+from .. import credentials
 
 try:
     # prefer pywin32-ctypes
@@ -127,7 +128,7 @@ def _delete_password(self, target):
             TargetName=target,
         )
 
-    def get_username_and_password(self, service, username):
+    def get_credential(self, service, username):
         res = None
         # get the credentials associated with the provided username
         if username:
@@ -136,10 +137,10 @@ def get_username_and_password(self, service, username):
         if not res:
             res = self._get_password(service)
             if not res:
-                return None, None
+                return None
         username = res['UserName']
         blob = res['CredentialBlob']
-        return username, blob.decode('utf-16')
+        return credentials.SimpleCredential(username, blob.decode('utf-16'))
 
 
 class OldPywinError:

keyring/core.py

@@ -70,22 +70,10 @@ def delete_password(service_name, username):
     _keyring_backend.delete_password(service_name, username)
 
 
-def get_username_and_password(service_name, username):
+def get_credential(service_name, username=None):
     """Get username and password from the specified service.
     """
-    try:
-        call = _keyring_backend.get_username_and_password
-    except AttributeError:
-        pass
-    else:
-        return call(service_name, username)
-
-    # The fallback behavior requires a username.
-    if username is not None:
-        password = _keyring_backend.get_password(service_name, username)
-        if password is not None:
-            return username, password
-    return None, None
+    return _keyring_backend.get_credential(service_name, username)
 
 
 def recommended(backend):

keyring/credentials.py

@@ -1,5 +1,6 @@
 import os
 import abc
+import collections
 
 from .py27compat import add_metaclass
 
@@ -20,22 +21,12 @@ def password(self):
         return None
 
 
-class SimpleCredential(Credential):
+class SimpleCredential(
+        collections.namedtuple('Credential', 'username password'),
+        Credential):
     """Simple credentials implementation
     """
 
-    def __init__(self, username, password):
-        self._username = username
-        self._password = password
-
-    @property
-    def username(self):
-        return self._username
-
-    @property
-    def password(self):
-        return self._password
-
 
 class EnvironCredential(Credential):
     """Source credentials from environment variables.

keyring/tests/test_backend.py

@@ -12,6 +12,7 @@
 
 from .util import random_string
 from keyring import errors
+from keyring import credentials
 
 __metaclass__ = type
 
@@ -135,21 +136,21 @@ def test_different_user(self):
         self.set_password('service2', 'user3', 'password3')
         assert keyring.get_password('service1', 'user1') == 'password1'
 
-    def test_username_and_password(self):
+    def test_get_credential(self):
         keyring = self.keyring
-        get = keyring.get_username_and_password
+        get = keyring.get_credential
 
-        assert get('service1', None) == (None, None)
+        assert get('service1', None) is None
         self.set_password('service1', 'user1', 'password1')
         self.set_password('service1', 'user2', 'password2')
 
-        # Using get_username_and_password may produce any of these results
-        valid = set((
-            ('user1', 'password1'),
-            ('user2', 'password2'),
-        ))
+        # Using get_credential may produce any of these results
+        valid = {
+            credentials.SimpleCredential('user1', 'password1'),
+            credentials.SimpleCredential('user2', 'password2'),
+        }
         # Passing None for username may result in no password
-        valid_or_none = valid | set(((None, None),))
+        valid_or_none = valid | {None}
 
         assert get('service1', None) in valid_or_none
         assert get('service1', 'user2') in valid