[Zope3-checkins] SVN: Zope3/trunk/src/zope/interface/ Added alsoProvides function that *adds* a new provided interface to an object.

[Amos Brocco]

Log message for revision 28165:
  Added alsoProvides function that *adds* a new provided interface to an object.
  

Changed:
  U   Zope3/trunk/src/zope/interface/__init__.py
  U   Zope3/trunk/src/zope/interface/declarations.py

-=-
Modified: Zope3/trunk/src/zope/interface/__init__.py
===================================================================
--- Zope3/trunk/src/zope/interface/__init__.py	2004-10-14 12:16:31 UTC (rev 28164)
+++ Zope3/trunk/src/zope/interface/__init__.py	2004-10-14 12:18:53 UTC (rev 28165)
@@ -62,6 +62,7 @@
 from zope.interface.declarations import providedBy, implementedBy
 from zope.interface.declarations import classImplements, classImplementsOnly
 from zope.interface.declarations import directlyProvidedBy, directlyProvides
+from zope.interface.declarations import alsoProvides
 from zope.interface.declarations import implements, implementsOnly
 from zope.interface.declarations import classProvides, moduleProvides
 from zope.interface.declarations import Declaration

Modified: Zope3/trunk/src/zope/interface/declarations.py
===================================================================
--- Zope3/trunk/src/zope/interface/declarations.py	2004-10-14 12:16:31 UTC (rev 28164)
+++ Zope3/trunk/src/zope/interface/declarations.py	2004-10-14 12:18:53 UTC (rev 28165)
@@ -846,8 +846,76 @@
         object.__provides__ = ClassProvides(object, cls, *interfaces)
     else:
         object.__provides__ = Provides(cls, *interfaces)
+        
+    
+def alsoProvides(object, *interfaces):
+    """Declare interfaces declared directly for an object
 
+      The arguments after the object are one or more interfaces or
+      interface specifications (IDeclaration objects).
 
+      The interfaces given (including the interfaces in the
+      specifications) are added to the interfaces previously
+      declared for the object.
+      
+      Consider the following example::
+
+        >>> from zope.interface import Interface
+        >>> class I1(Interface): pass
+        ...
+        >>> class I2(Interface): pass
+        ...
+        >>> class IA1(Interface): pass
+        ...
+        >>> class IA2(Interface): pass
+        ...
+        >>> class IB(Interface): pass
+        ...
+        >>> class IC(Interface): pass
+        ...
+        >>> class A(object): implements(IA1, IA2)
+        ...
+        >>> class B(object): implements(IB)
+        ...
+
+        >>> class C(A, B):
+        ...    implements(IC)
+
+        >>> ob = C()
+        >>> directlyProvides(ob, I1)
+        >>> int(I1 in providedBy(ob))
+        1
+        >>> int(I2 in providedBy(ob))
+        0
+        >>> int(IA1 in providedBy(ob))
+        1
+        >>> int(IA2 in providedBy(ob))
+        1
+        >>> int(IB in providedBy(ob))
+        1
+        >>> int(IC in providedBy(ob))
+        1
+        
+        >>> alsoProvides(ob, I2)
+        >>> int(I1 in providedBy(ob))
+        1
+        >>> int(I2 in providedBy(ob))
+        1
+        >>> int(IA1 in providedBy(ob))
+        1
+        >>> int(IA2 in providedBy(ob))
+        1
+        >>> int(IB in providedBy(ob))
+        1
+        >>> int(IC in providedBy(ob))
+        1
+        
+      The object, ``ob`` provides ``I1``, ``I2``, and whatever interfaces
+      instances have been declared for instances of ``C``. Notice that the
+      alsoProvides just extends the provided interfaces.
+    """
+    directlyProvides(object, directlyProvidedBy(object), *interfaces)
+
 class ClassProvidesBasePy(object):
 
     def __get__(self, inst, cls):