Request for an Unmodifiable Set

[sethladd]

I see an unmodifiable list view and map view in dart:collection, but didn't find an unmodifiable set view. Do we have something like that? If not, could we consider adding it?

(request from customer)

[zoechi]

I usually use UnmodifiableListView for sets but a real UnmodifiableSetView would be nice to make it more clear for the user of the API what is actually returned.

[lrhn]

You can use the one in package:collection (http://www.dartdocs.org/documentation/collection/1.1.3/index.html#collection/dart:pkg-collection-wrappers.UnmodifiableSetView).
We have unmodifiable list and map mainly because we have list and map literals and several instances of API that returns unmodifiable lists or maps (e.g., Invocation). Unmodifiable sets are much more rare.

[sethladd]

Thanks for the follow up! I understand that we want to work towards smaller core libraries, and that some functionality will be in packages.

cc @Hixie

[Hixie]

We should have set literals also. There are places in Flutter's codebase right now where we're working around the lack of Set literals, FWIW.

[sethladd]

See: #3792

[Hixie]

Right. I'm just saying that if the argument is that we shouldn't have an UnmodifiableSet because we don't have a Set literal, that that's fine, since we should have a Set literal anyway. :-)