Setting<T> constructor

Setting<T>({ required Settings settings, required String key, required T decode(RawSettingValue), required RawSettingValue encode(T), })

A single setting that exposes a type T to the consuming application.

The _key is a function that returns the key for the setting. The _decode function is used to convert the raw value from the underlying storage to the type T. The _encode function is used to convert the value of type T to a raw value that can be stored in the underlying storage.

Implementation

Setting({
  required Settings settings,
  required String key,
  required T Function(RawSettingValue) decode,
  required RawSettingValue Function(T) encode,
})  : _decode = decode,
      _encode = encode,
      _key = key,
      _settings = settings {
  final $key = _key;
  value = _settings._group.writable(
    _decode(_toRawValue(_settings._storage.get($key))),
    name: '${$key}_value',
  );
  // Any time `value` changes, persist the new value to the underlying storage.
  _settings._group.effect(
    () async {
      final $value = value.value;
      final $key = _key;
      if (_settings._storage.get($key) != $value) {
        final encoded = _encode($value);
        await switch (encoded) {
          StringSettingValue() =>
            _settings._storage.setString($key, encoded.value),
          IntSettingValue() => _settings._storage.setInt($key, encoded.value),
          DoubleSettingValue() =>
            _settings._storage.setDouble($key, encoded.value),
          BoolSettingValue() =>
            _settings._storage.setBool($key, encoded.value),
          StringListSettingValue() =>
            _settings._storage.setStringList($key, encoded.value),
          NullSettingValue() => _settings._storage.remove($key),
        };
      }
    },
    name: '${$key}_effect',
  );
}