ImmutableMap::of should accept more entries · Issue #2071 · google/guava (original) (raw)

I'm using ImmutableMap for building structures that I can then automatically serialize to JSON, like the following adapted from http://json.org/example:

Map j = ImmutableMap.of( "id", id, "title", title, "debug", "on", "window", ImmutableMap.of( "title", "Window title", "name", "window_1", "width", 500, "height", 500 ) );

Coming from Python where JSON can be used in source code as-is, the above is a very nice alternative in Java land and I couldn't think of a way to make it any better, syntax-wise. However, I hit the limit of the maximum 5 key-value pairs of ImmutableMap::of, and then I had to use rather ugly workarounds (with Builder or alternatively splitting a big Map up into two and joining them together again...).

I fully understand that there is no variable arguments overload like in ImmutableSet::of -- you couldn't guarantee at compile-time that the number of ImmutableMap::of arguments is even (to form key-value pairs), it would fail at run-time, and we don't want that.

I also understand that there probably is some resistance in providing a high number of overloads. However, I still think the limit of 5 entries is too low. And resorting to Builder is just plain ugly in some cases. I therefore propose to raise the number of overloads to 10, as this should cover most use cases and will create less headache for users. On the implementation side it is a trivial change and I don't see any problem.