A test of whether or not your
converter function should run in response
to a State change. For advanced use only.
Some changes to the State of your application will mean your
function can't produce a useful ViewModel. In these cases, such as when
performing exit animations on data that has been removed from your Store,
it can be best to ignore the State change while your animation completes.
To ignore a change, provide a function that returns true or false. If the returned value is true, the change will be ignored.
If you ignore a change, and the framework needs to rebuild the Widget, the
builder function will be called with the latest
ViewModel produced by
typedef IgnoreChangeTest<S> = bool Function(S state);