# HG changeset patch
# User Thierry Florac <thierry.florac@onf.fr>
# Date 1516977056 -3600
# Node ID 5b80ba4fba8ef02d613d8006a0b6071aa3f1113d
# Parent  0fcad7725bdc134197c36f6094203debd4e66178
Added 'inherit' interface and module to handle inheritance

diff -r 0fcad7725bdc -r 5b80ba4fba8e src/pyams_utils/inherit.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/pyams_utils/inherit.py	Fri Jan 26 15:30:56 2018 +0100
@@ -0,0 +1,87 @@
+#
+# Copyright (c) 2008-2015 Thierry Florac <tflorac AT ulthar.net>
+# All Rights Reserved.
+#
+# This software is subject to the provisions of the Zope Public License,
+# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
+# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
+# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
+# FOR A PARTICULAR PURPOSE.
+#
+
+__docformat__ = 'restructuredtext'
+
+
+# import standard library
+
+# import interfaces
+from pyams_utils.interfaces.inherit import IInheritInfo
+
+# import packages
+from pyams_utils.traversing import get_parent
+from pyams_utils.zodb import volatile_property
+from zope.interface import implementer, Interface
+from zope.location import Location
+from zope.schema.fieldproperty import FieldProperty
+
+
+@implementer(IInheritInfo)
+class BaseInheritInfo(Location):
+    """Base inherit class"""
+
+    adapted_interface = Interface
+    target_interface = Interface
+
+    _inherit = FieldProperty(IInheritInfo['inherit'])
+
+    @volatile_property
+    def parent(self):
+        return get_parent(self.__parent__, self.target_interface, allow_context=False)
+
+    @property
+    def can_inherit(self):
+        return self.target_interface.providedBy(self.parent)
+
+    @property
+    def inherit(self):
+        return self._inherit if self.can_inherit else False
+
+    @inherit.setter
+    def inherit(self, value):
+        if self.can_inherit:
+            self._inherit = value
+        del self.parent
+
+    @property
+    def no_inherit(self):
+        return not bool(self.inherit)
+
+    @no_inherit.setter
+    def no_inherit(self, value):
+        self.inherit = not bool(value)
+
+
+class InheritedFieldProperty(object):
+    """Inherited field property"""
+
+    def __init__(self, field, name=None):
+        if name is None:
+            name = field.__name__
+
+        self.__field = field
+        self.__name = name
+
+    def __get__(self, inst, klass):
+        if inst is None:
+            return self
+        inherit_info = IInheritInfo(inst)
+        if inherit_info.inherit:
+            return getattr(inherit_info.adapted_interface(inherit_info.parent), self.__name)
+        else:
+            return getattr(inst, '_{0}'.format(self.__name))
+
+    def __set__(self, inst, value):
+        inherit_info = IInheritInfo(inst)
+        if not (inherit_info.can_inherit and inherit_info.inherit):
+            setattr(inst, '_{0}'.format(self.__name), value)
diff -r 0fcad7725bdc -r 5b80ba4fba8e src/pyams_utils/interfaces/inherit.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/pyams_utils/interfaces/inherit.py	Fri Jan 26 15:30:56 2018 +0100
@@ -0,0 +1,44 @@
+#
+# Copyright (c) 2008-2015 Thierry Florac <tflorac AT ulthar.net>
+# All Rights Reserved.
+#
+# This software is subject to the provisions of the Zope Public License,
+# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
+# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
+# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
+# FOR A PARTICULAR PURPOSE.
+#
+
+__docformat__ = 'restructuredtext'
+
+# import standard library
+
+# import interfaces
+from pyramid.interfaces import ILocation
+
+# import packages
+from zope.interface import Attribute
+from zope.schema import Bool
+
+from pyams_utils import _
+
+
+class IInheritInfo(ILocation):
+    """Inheritance info"""
+
+    adapted_interface = Attribute("Context or parent adapted interface")
+
+    target_interface = Attribute("Parent target interface")
+
+    parent = Attribute("First parent supporting target interface")
+
+    can_inherit = Attribute("Can inherit from parent?")
+
+    inherit = Bool(title=_("Inherit from parent?"),
+                   required=False,
+                   default=True)
+
+    no_inherit = Bool(title=_("Don't inherit from parent?"),
+                      required=False,
+                      default=False)