This is an OO design question. For my task, I have some objects and a particular file format that encodes them. I want to be able to read the file and create those objects. The Stream API seems like the right way to do this, but I'm not sure how to encapsulate my code. I see these options: ⢠Create a new class (subclass of Object) that implements #next to return the next object in some underlying stream. Pro: very simple, one place with all the code. Con: what about the rest of the Stream and/or Collection APIs? Is it wise to delegate everything else to the underlying stream with #doesNotUnderstand:? ⢠Create a new class, subclass of Stream, that implements #next like the above. Pro: still pretty simple, not sure what is needed to implement the API completely (I did add a method #atEnd). Con: not sure if more methods are missing; unclear about initialization (overrode class>>#on: to call #basicNew). This seems close to the right approach but I'm unsure. ⢠Create a method #nextFoo on the existing Stream class. Pro: very simpleâno new class. Con: nextFoo doesn't integrate well with the rest of the API (#do: for instance), not sure this is clean or wise. ⢠Ignore the Stream classes altogether. Pro: No chance of misundestanding. :) Con: everything else. Advice? Thanks for your time, â Daniel Lyons