CredentialManager: Store passwords in system keyring

Credential Manager is used for safely storing passwords in system's keyring services.

Orange/widgets/credentials.py

@@ -0,0 +1,38 @@
+import keyring
+
+SERVICE_NAME = 'Orange3 - {}'
+
+
+class CredentialManager:
+    """
+    Class for storage of passwords in the system keyring service.
+    All attributes of this class are safely stored.
+
+    Args:
+        service_name (str): service name used for storing in keyring.
+
+    Examples:
+        >>> cm = CredentialManager('Widget Name')
+        >>> cm.username = 'Orange'      # store username
+        >>> cm.password = 'Secret'      # store password
+
+        >>> cm.username                 # get username
+        'Orange'
+        >>> cm.password                 # get password
+        'Secret'
+    """
+    def __init__(self, service_name):
+        self.__dict__['__service_name'] = SERVICE_NAME.format(service_name)
+
+    @property
+    def service_name(self):
+        return self.__dict__['__service_name']
+
+    def __setattr__(self, key, value):
+        keyring.set_password(self.service_name, key, value)
+
+    def __getattr__(self, item):
+        return keyring.get_password(self.service_name, item)
+
+    def __delattr__(self, item):
+        keyring.delete_password(self.service_name, item)

Orange/widgets/tests/test_credentials.py

@@ -0,0 +1,12 @@
+import unittest
+
+from Orange.widgets.credentials import CredentialManager
+
+
+class CredentialManagerTests(unittest.TestCase):
+    def test_credential_manager(self):
+        cm = CredentialManager('Orange')
+        cm.key = 'Foo'
+        self.assertEqual(cm.key, 'Foo')
+        del cm.key
+        self.assertEqual(cm.key, None)

requirements-core.txt

@@ -8,3 +8,5 @@ xlrd>=0.9.2
 chardet>=2.3.0
 # Multiprocessing abstraction
 joblib>=0.9.4
+keyring
+keyrings.alt    # for running test on travis