Foo.Of{Int,Long,Double} naming convention (original) (raw)

Brian Goetz brian.goetz at oracle.com
Mon Dec 31 08:20:59 PST 2012

There are two things here:

The naming convention was proposed as a means of reducing the perceived surface area in cases where separate interfaces are needed.

There are definitely cases where separate interfaces are needed. For example, Iterator. If we have a stream of ints, we need some way to ask for the ints without boxing. This could be PrimitiveIterator.OfInt, IntIterator (Interator?), IntCursor, etc. So this thread is mostly about "If we do find ourselves needing separate interfaces, what should we call them."

Separately, we have been trying to not specialized when we can get away with doing so.

On 12/31/2012 2:24 AM, David Holmes wrote:

Does this really buy enough to make distinct interfaces worth their weight?

David On 24/12/2012 3:44 AM, Brian Goetz wrote: For types that have primitive specializations that are subtypes of the base type (e.g., MutableReducer), we've been converging on a naming convention that puts the subtypes as nested interfaces. For example:

interface MutableReducer<T,R> { // reducer methods interface OfInt extends MutableReducer<Integer,R> { ... } interface OfLong extends MutableReducer<Integer,R> { ... } } The motivation here is (a) reduce the javadoc surface area, (b) groups related abstractions together, (c) makes it clear that these are subsidiary abstractions, and (d) keep the cut-and-paste stuff together in the code. The use site also looks pretty reasonable: class Foo implements MutableReducer.OfInt { ... } This shows up in Sink, IntermediateOp, TerminalOp, MutableReducer, NodeBuilder, Node, Spliterator, etc. (It also shows up in concrete implementation classes like ForEachOp, MatchOp, and FindOp, though these will not be public and so (a) doesn't really apply to these.) Are we OK with this convention? It seems to have a tidying effect on the codebase, the documentation, and client usage, and mitigates the pain of the primitive specializations. (There will be grey areas where its applicability is questionable; we can discuss those individually, but there are a lot of things that it works for.)

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