Pharo now uses slots to describe instance variables. Booleans no longer need to be separate instance variables, several can be mapped to a bit in one instance variable. Printing this in a workspace returns the set of classes having instances with more than one boolean instVar. It doesn't detect lazy initialized ones, or classes with no current i…

gistfile1.txt

|set| 
set := IdentitySet new. 
Object allSubclasses do: [ :aClass | 
        |varSize coll nr candidate | 
        candidate := false. 
        varSize := aClass instSize. 
        coll := aClass allInstances. 
        nr := 10 min: coll size. 
        (coll first: nr) do: [ :anInstance | 
                |value nrBoolean| 
                nrBoolean := 0. 
                1 to: varSize do: [ :varIndex | 
                        value := anInstance instVarAt: varIndex. 
                        value class = True ifTrue: [ nrBoolean := nrBoolean + 1  ]. 
                        value class = False ifTrue: [ nrBoolean := nrBoolean + 1  ]]. 
                nrBoolean >1 ifTrue: [ candidate := true ]   ]. 
        candidate ifTrue: [ set add: aClass ]]. 
set.