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state watcher

Provided

A Provided references an independent state which can be manually updated over time.

A Provided can be easily declared:

// Here we declare a Provided with an initial state of 0.
final refCounter = Provided((_) => 0);

Sometimes a Provided can have some dependencies which are only read when the state is created. For example a repository can have a dependency on an api client:

/// Use read to inject dependencies when creating your instances.
final refRepository = Provided((read) {
  return Repository(apiClient: read(refApiClient));
});

When you have a Provided that has a meaning only when it is overriden, it can be useful to create it without an initial value:

final refCurrentItem = Provided<Item>.undefined();

There are two methods on the store object to modify the state of a Provided:

// To write a new value independent of the previous one:
store.write(refProvided, 10);


// To write a new value which depends of the previous one:
store.update(refProvided, (x) => x + 1);