Hi guys I'm on holidays (no book no mooc no bugs just playing magic good music and hacking a bit) and I wanted to implemented a fun object that learn from Object by copying the methods. ProtoObject subclass: #ATMinimalLearningObject instanceVariableNames: '' classVariableNames: '' package: 'MiniActalk2' ATMinimalLearningObject >> doesNotUnderstand: aMessage | sel | sel := aMessage selector. Transcript show: 'Does not understand ', sel printString ; cr. ^ (Object includesSelector: sel) ifTrue: [ self addFromObjectSelector: sel. aMessage sendTo: self ] ifFalse: [ super doesNotUnderstand: aMessage ]. ATMinimalLearningObject >> addFromObjectSelector: aSelector | method | method := OpalCompiler new class: self class; source: (Object sourceCodeAt: aSelector); compile. self class addSelector: aSelector withMethod: method. ATMinimalLearningObject subclass: #ATProtozoid instanceVariableNames: 'ff' classVariableNames: '' package: 'MiniActalk2' Now it is working but I have the impression that we may have a problem. When I do ATProtozoid new instVarAt: 1 I get the following definition for instVarAt: instVarAt: t1 self error: 'Decompilation failed' but Object sourceCodeAt: #instVarAt: returns the correct string. 'instVarAt: index "Primitive. Answer a fixed variable in an object. The numbering of the variables corresponds to the named instance variables, followed by the indexed instance variables. Fail if the index is not an Integer or is not the index of a fixed variable. Essential. See Object documentation whatIsAPrimitive." <primitive: 173 error: ec> self primitiveFailed' May be the compile is not logging the method body. But since the compiler is full uncommented this is super nice to learn and get empowered. Stef