Model class and Datastore annotations should not depend on Mirrors

[nicolasgarnier]

Model class and Datastore annotations (like @kind, @StringProperty()...) should be in a separate importable library and not depend on the Mirrors package. It's common practice to have the model classes shared between the Client and the Server when both are written in Dart. Currently an @MirrorUsed() annotation will fix the issue of large generated code size but it would be nicer not to have to use it.

[sethladd]

cc @eernstg

[eernstg]

Seems like the only actual dependency is that model_db_impl.dart needs dart:mirrors. The import of dart:mirrors cannot simply be moved from db.dart to model_db_impl.dart because that file is a 'part' of db.dart, but it looks like the dependency on dart:mirrors could at least be encapsulated by refactoring that file from being a 'part' to a 'library'. In the case of https://github.com/dart-lang/reflectable the transformer will eliminate the dependency on dart:mirrors entirely; but I don't know anything about the details of this package, so I won't make any wild guesses about whether that approach would work here.

[nicolasgarnier]

+1 I also think it's just a matter of doing a refactoring and putting the xxxProperty, Kind,IdType, Model and ExpandoModel classes into their own library.

[sigurdm]

Maybe when macros land...