Comment #4 on issue 3224 by luc.fabresse: Migrating MethodReference to MethodReferenceWithSource http://code.google.com/p/pharo/issues/detail?id=3224 some comments. We must add a hash method on SourcedMethodReference. I propose: SourcedMethodReference>>hash "Answer a SmallInteger whose value is related to the receiver's identity." ^ super hash bitXor: self sourcePointer All instances of SourcedMethodReference should (*must*) have a defined sourcePointer (not be nil) at instanciation time. But it seems that it is not the case since some initializing methods from MethodReference are not redefined in SourcedMethodReference: MethodReference>>setClass:methodSymbol: MethodReference>>setClassAndSelectorIn: MethodReference>>setClassSymbol:classIsMeta:methodSymbol:stringVersion: MethodReference>>setClass:methodSymbol:stringVersion: For example, in SystemNavigation a lot of methods use: SourcedMethodReference new setClass: class methodSymbol: sel which leave sourcePointer uninitialized. Did these changes break some tests?