state_groups

Stateless state management solution

Most state management solutions are overly convoluted because they try to do two things: manage the internal state and update the visible state. State groups, on the other hand, only updates the visible state. You have to manage the internal state yourself. This way it can be significantly simpler than other state management solutions.

Usage

Version 0.3.1 significantly simplifies the process. The following method is preferred although you can still use the legacy method (described at the end).

This package works by notifying State in a StatefulWidget. To do so simply convert the State that your State inherits from to a SyncState. So

class FooState extends State<Foo>

becomes

class FooState extends SyncState<void, Foo>

Notifying

To notify all the SyncStates of a given type simply call updateAll<T>() where T is the type you want to notify. IE:

updateAll<FooState>();

If you want to send more complicated messages call forEachState<T>(void Function(T)) again with T being the type you want to notify. IE:

forEachState<FooState>((FooState state) {
	state.someInternalMethod();
});

Usage (Legacy)

Creating State Groups

First create a state group. For this example we will create a global variable although they don't have to be global.

StateGroup exampleStateGroup = StateGroup();

You can also specify a generic type as the message type. Here we'll use void as we won't be sending any messages but if you wanted to send a message you could use an enum instead.

StateGroup<void> exampleStateGroup = StateGroup<void>();

Registering To A StateGroup

There are two steps here. First change the state class to extend from SyncState instead of State. This will also requiring adding an additional generic type. This should be the same generic type used in the previous step We'll leave this as void for now.

class FooState extends State<Foo>

becomes

class FooState extends SyncState<void, Foo>

Then make the constructor call super with the state group you would like to subscribe to.

FooState() : super(exampleStateGroup);

Notifying A StateGroup

Now you can notify a StateGroup whenever you want all the members of the group to update or check if they should update. To do so use the notifyAll() command like so:

exampleStateGroup.notifyAll();

And that's it. The StateGroup will handle everything else automatically.

SyncStateBuilder

If this is too much work for you there is also SyncStateBuilder<T> which works as a SyncState<void>. It should be enough if all you want is to have the UI update on a notification but it does not support custom update behaviour.