Changed custom feature so that params aren't added to globals.

There is probably a better way of doing this, but currently
parseCustomFile can modify globals (e.g. TOPOS) as well as
instance variables (self.validate) and classes (e.g. MyTopo),
which are also in the global name space.

Inconveniently enough, lambdas don't seem to be full closures
in Python; if they were, this trickiness would be unnecessary.

Even so, using execfile() seems like it might be a bit dubious...

bin/mn

@@ -81,19 +81,30 @@ class MininetRunner( object ):
         self.parseArgs()
         self.setup()
         self.begin()
-
-    def parseCustomFile( self, custom ):
-        "Parse custom file and add params before parsing cmd-line options."
-        if os.path.isfile( custom ):
-            execfile( custom, globals(), globals() )
-            if 'topos' in globals(): TOPOS.update( topos )
-            if 'switches' in globals(): SWITCHES.update( switches )
-            if 'hosts' in globals(): HOSTS.update( hosts )
-            if 'controllers' in globals(): CONTROLLERS.update( controllers )
-            if 'validate' in globals(): self.validate = validate
+  
+    def setCustom( self, name, value ):
+        print "got", self, name, value
+        if name in ( 'topos', 'switches', 'hosts', 'controllers' ):
+            # Update dictionaries
+            param = name.upper()
+            globals()[ param ].update( value )
+        elif name == 'validate':
+            # Add custom validate function
+            self.validate = value
         else:
-            raise Exception( 'could not find custom file: %s' % custom )
-
+            # Add or modify global variable or class
+            globals()[ name ] = value
+        
+    def parseCustomFile( self, fileName ):
+        "Parse custom file and add params before parsing cmd-line options."
+        custom = {}
+        if os.path.isfile( fileName ):
+            execfile( fileName, custom, custom )
+            for name in custom:
+                self.setCustom( name, custom[ name ] )
+        else:
+            raise Exception( 'could not find custom file: %s' % fileName )
+        
     def parseArgs( self ):
         """Parse command-line args and return options object.
            returns: opts parse options dict"""
@@ -161,7 +172,7 @@ class MininetRunner( object ):
                              port=self.options.port )
 
         if self.validate:
-            self.validate(self.options)
+            self.validate( self.options )
 
         controllerParams = ControllerParams( 0x0a000000, 8 ) # 10.0.0.0/8
         inNamespace = self.options.inNamespace