Hi, I totally agree that the "base programmer" needs to be supported, but on the other hand we should offer the tools to extend Moose. It is just that I do not understand exactly what the advantages/ disadvantages are, and I propose to start a discussion on that. I do not understand exactly the solution, but here is what I understood as the reasons for wide classes: 1. extend the state of a class from another package 2. save memory by only allocating a instance variable slot when it is used 3. (speed?) 1. In VW we can extend the methods and that allowed us to have a nice extensible architecture. In the same way, we should be able to extend the state as well, for example for caching results performed by a method extension. That is why currently, we have __state__ in each entity that has dictionaries for storing such results, and we wrap the calls to __state__ in setters and getters. For example, in DynaMoose we have: FAMIXClass>>instances ^self __state__ attributeGet: #instances initializer: [ OrderedCollection new ] FAMIXClass>>instances: aCollection ^self __state__ attributeSet: #instances value: aCollection The symbol is only used here. All tools work nicely with that (actually, in VW looking for senders of a method will also get you the usages of the symbol). This mechanism is crucial for extending the meta-model. The wide classes solution would pose the same overhead on the programmer. 2. The second reason for the wide classes is to reduce the memory footprint, because you will only get a slot if you use it. The current solution will create a dictionary for all instance variables extensions and an entry for each of them. I would be curious to see what the difference is. 3. Speed. I am definitely not sure about this point, but wide classes should be faster than looking into a dictionary. But, I do not believe this has a real impact over the overall performance, in particular given that the dictionary are rather small. Of course, you can just bash anything I wrote here :) Doru -- www.tudorgirba.com www.tudorgirba.com/blog "There are no old things, there are only old ways of looking at them."