In Squeak 3.5, oldFileOrNoneNamed: fileName "If the file exists, answer a read-only FileStream on it. If it doesn't, answer nil."
| fullName | fullName _ FileStream fullName: fileName. (FileStream concreteStream isAFileNamed: fullName) ifTrue: [^ FileStream concreteStream readOnlyFileNamed: fullName] ifFalse: [^ nil].
should fullName _ FileStream fullName: fileName. be fullName _ self fullName: fileName. ?
-Volker