Encountered by F Geiger ( http://groups.google.com/group/boolang/browse_thread/thread/2d0fd0beeb0d5671/a4e22c3bd8371cd1#a4e22c3bd8371cd1 ) rwar1 has an indexer. rwar2 derives from rwar1 and thus inherits rwar1's indexer. However, if source code using rwar2 is visited before information about rwar2 and rwar1 has been collected, then Boo doesn't know that rwar2 has inherited an indexer from rwar1. This results in incorrect compiler errors. RWAR1.BOO class rwar1: """Description of rwar1""" def constructor(): pass self[i as int]: get: return 0 set: pass RWAR2.BOO class rwar2(rwar1): """Description of rwar2""" def constructor(): pass RWARTEST.BOO class rwartest: """Description of rwartest""" def constructor(): pass y = rwar2() y[0] CONSOLE COMMANDS USED – note the order i pass in files seems to be the order boo visits classes*** D:\Boo\boo\trunk\bin\net-2.0>booc -r:mapack -r:boo.lang.useful -t:library d:\temp\strangething\rwartest.boo d:\temp\StrangeThing\rwar1.boo d:\temp\StrangeThing\rwar2.boo Boo Compiler version 0.7.6.2204 (CLR v2.0.50727.42) d:\temp\strangething\rwartest.boo(11,1): BCE0048: Type 'StrangeThing.rwar2' does not support slicing. 1 error(s). D:\Boo\boo\trunk\bin\net-2.0>booc -r:mapack -r:boo.lang.useful -t:library d:\temp\StrangeThing\rwar1.boo d:\temp\StrangeThing\rwar2.boo d:\temp\strangething\rwartest.boo Boo Compiler version 0.7.6.2204 (CLR v2.0.50727.42) (compile worked)