From: Tony Mack <tmack@cs.princeton.edu>
Date: Thu, 5 Aug 2010 23:33:41 +0000 (+0000)
Subject: BaseApi.get_interface_manager() wraps the manager module/library in a ManagerWrapper... 
X-Git-Tag: sfa-1.0-0~85
X-Git-Url: http://git.onelab.eu/?p=sfa.git;a=commitdiff_plain;h=2bba5331db88542f6d646ae7aa39df3dd9e8e973

BaseApi.get_interface_manager() wraps the manager module/library in a ManagerWrapper class before returning it
---

diff --git a/sfa/util/api.py b/sfa/util/api.py
index 8343969e..cda8c887 100644
--- a/sfa/util/api.py
+++ b/sfa/util/api.py
@@ -95,6 +95,27 @@ def import_deep(name):
         mod = getattr(mod, comp)
     return mod
 
+class ManagerWrapper:
+    """
+    This class acts as a wrapper around an SFA interface manager module, but
+    can be used with any python module. The purpose of this class is raise a 
+    SfaNotImplemented exception if the a someone attepmts to use an attribute 
+    (could be a callable) thats not available in the library by checking the
+    library using hasattr. This helps to communicate better errors messages 
+    to the users and developers in the event that a specifiec operation 
+    is not implemented by a libarary and will generally be more helpful than
+    the standard AttributeError         
+    """
+    def __init__(self, manager, interface):
+        self.manager = manager
+        self.interface = interface
+        
+    def __getattr__(self, method):
+        
+        if not hasattr(self.manager, method):
+            raise SfaNotImplemented(method, self.interface)
+        return getattr(self.manager, method)
+        
 class BaseAPI:
 
     cache = None
@@ -158,8 +179,11 @@ class BaseAPI:
             manager_module = manager_base + ".component_manager_%s" % mgr_type
         else:
             raise SfaAPIError("No manager for interface: %s" % self.interface)  
-        manager = __import__(manager_module, fromlist=[manager_base])   
- 
+        manager = __import__(manager_module, fromlist=[manager_base])
+        # this isnt necessary but will hlep to produce better error messages
+        # if someone tries to access an operation this manager doesn't implement  
+        manager = ManagerWrapper(manager, self.interface)
+
         return manager
 
     def callable(self, method):
diff --git a/sfa/util/faults.py b/sfa/util/faults.py
index 5880fd90..8bf71e81 100644
--- a/sfa/util/faults.py
+++ b/sfa/util/faults.py
@@ -55,8 +55,10 @@ class SfaPermissionDenied(SfaFault):
         SfaFault.__init__(self, 108, faultString, extra)
 
 class SfaNotImplemented(SfaFault):
-    def __init__(self, extra = None):
-        faultString = "Not fully implemented"
+    def __init__(self, interface=None, extra = None):
+        faultString = "Not implemented"
+        if interface:
+            faultString += " at interface " + interface 
         SfaFault.__init__(self, 109, faultString, extra)
 
 class SfaAPIError(SfaFault):
diff --git a/sfa/util/nodemanager.py b/sfa/util/nodemanager.py
index 99575c68..1671b9d6 100644
--- a/sfa/util/nodemanager.py
+++ b/sfa/util/nodemanager.py
@@ -15,7 +15,6 @@ class NodeManager:
     
     def __call__(self, *args):
         method = self.method
-        ### WARNING -- hardwired name needs to be computed
         sfa_slice_prefix = self.config.SFA_CM_SLICE_PREFIX 
         sfa_slice = sfa_slice_prefix + "_sfacm"
         python = "/usr/bin/python"