Riverpod: why use a Provider instead of a global final variable-CodePudding

I came across some code using Riverpod, for example for retrieving http data with Dio, using a Riverpod provider as below:

final client = Provider((ref) => Dio());

then use it to fetch data:

final response = await ref.watch(client).getUri<Map<String, Object?>>(uri, cancelToken: cancelToken);

Why use a Riverpod Provider for the client as it reference will never change and not use a global variable instead?:

final clientDio = Dio();

final response = await clientDio.getUri<Map<String, Object?>>(uri, cancelToken: cancelToken);

CodePudding user response：

Using a provider allows replacing the implementation with a different one using overrides.

For an HTTP client, this can allow replacing it with a fake one that returns pre-determined responses. This can be useful for testing or development/debugging purposes.