Frequently Asked Questions
If you have a question, please make a discussion post and I may post the outcome here!
Do state side effects trigger rebuilds internally?
Yes! As a general rule of thumb,
any side effect that mutates some state external to the build
and then returns that state or a value dependent upon that state
will likely trigger rebuilds.
As an example, setState updates a value extenal to the capsule build itself (it is a callback),
and use.state returns state, so it triggers a rebuild.
While use.memo updates a state value, it is done within the build itself,
so it doesn't trigger any rebuilds.
Does rebuild() trigger rebuilds immediately? Or can you call it back-to-back?
For capsules: yes.
Calling rebuild() multiple times in a row will trigger multiple rebuilds.
This is also true for calling different setStates or similar back-to-back;
multiple rebuilds are triggered.
As this is often undesirable, ReArch has "side effect transactions"
that can run a bunch of side effects in one batch to result in one rebuild.
final runTransaction = use.transactionRunner();
void updateMultipleEffectsInOneBuild() {
runTransaction(() {
setState1(1234);
setState2(4321);
invalidateFuture();
somethingElseThatMayRebuild();
});
}
For Flutter widgets: no.
Rebuilds are automatically batched together on the next frame via flutter’s build scheduler
(ReArch internally calls
Element.markNeedsBuild).
You can read more about "side effect transactions" here.
(Dart/Flutter) What is the purpose of SideEffectRegistrar.register()?
use.register(), as it is often seen, is meant to implement rather low-level side effects,
and thus you often won't need to use it directly.
It essentially is a combination of a way to access the outside world
(via the SideEffectApi),
coupled with a way to call some certain function only on the first build,
which can be used to persist state across builds.
(Dart/Flutter) How can I use ReArch with fpdart? Specifically, the Options clash.
See https://github.com/GregoryConrad/rearch-dart/issues/79#issuecomment-1889770035 and https://github.com/GregoryConrad/rearch-dart/issues/79#issuecomment-1890421419.