If we see CompiledMethodTrailer >> sourceCode "Answer the source code of compiled method. Note: it does not attempts to read from source files using sourcePointer, nor reconstruct the source code using temp names" (kind == #EmbeddedSourceQCompress or: [ kind == #EmbeddedSourceZip ]) ifTrue: [ ^ data ]. kind == #SourceBySelector ifTrue: [ ^ method methodClass getSourceCodeBySelector: method selector ]. kind == #SourceByStringIdentifier ifTrue: [ ^ method methodClass getSourceCodeByIdentifier: data ]. ^ nil But neither #getSourceCodeBySelector: nor #getSourceCodeByIdentifier: are implemented. In fact, it is easy to modify their test and make them red. Change #testSourceBySelectorEncoding or #testSourceByIdentifierEncoding and add a send to #sourceCode. Example: testSourceBySelectorEncoding | trailer | trailer := CompiledMethodTrailer new. trailer setSourceBySelector. self assert: (trailer kind == #SourceBySelector ). self assert: (trailer size = 1). trailer sourceCode. So...I don't know why they are not implemented, but if this was work "unfinished", we should at least make that clear and not to appear that it is supported but at the end it is not. So, if that's the case, I suggest to put nice comments explaining that and in addition implement: Behavior >> getSourceCodeBySelector: ^ self notYetImplemented Behavior >> getSourceCodeByIdentifier: ^ self notYetImplemented What do you think ? -- Mariano http://marianopeck.wordpress.com