Hi.

Look at UndefinedObject instance side methods. You will see class hierarchy protocol. For example nil understands #subclasses message:

nil subclasses "==> {ProtoObject}"

It implemented like this:

UndefinedObject >>subclassesDo: aBlock
"Evaluate aBlock with all subclasses of nil.�� Others are not direct subclasses of Class."

^ Class subclassesDo: [:cl |��
cl isMeta ifTrue: [aBlock value: cl soleInstance]].

So my question is: why it needs to be like that? And does it really needed?

I removed all this methods and not saw any problem.��