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949

Abstract

fix</pre></div>It will add underscore in front of variable a:<div id="39a9"><pre>fn main() { let _a = 10; }</pre></div>3 Clippy:We can use it to catch common mistakes and improve your Rust code.To install clippy , by running:<div id="bb1c"><pre>rustup component add clippy</pre></div>Like we want to use PI value,<div id="7232"><pre>fn main() { let a = 3.14; let b = 2.0; println!("{}", a * b); }</pre></div>We run :<div id="58e4

Options

"><pre>cargo clippy</pre></div>It will tell us to use PI defined in standard library for more precise.So we can change our code to :<div id="b409"><pre>use std::f32::consts::PI;

fn main() { let a = PI; let b = 2.0; println!("{}", a * b); }</pre></div>4 rust-analyzerIt’s an extension, we can install it by searching rust-analyzer in extensions in vs code. It will make vs code gain abilities such as type definition, code completion, syntax highlighting and inline errors.</article></body>

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Flutter — Offline First

Offline is my default state, a connection is a nice addition

Christian Muehle

To support being Offline first, I’ve added a new feature that monitors the client device connection and updates a ‘Connection’ state with two values ‘Online’ & ‘Offline’.

In the next post in the mini ‘_Offline First_’ series, I will use the new connectivity detection, to point data requests at a local DB when offline, and to sync them when the online API is available.

Ta Da

It was easy to implement the feature using the connectivity_plus package.

It just required a new provider:

// Package imports:
import 'package:connectivity_plus/connectivity_plus.dart';
import 'package:digestable_prologue/connection_detector/model/network_connection_state.dart';
import 'package:hooks_riverpod/hooks_riverpod.dart';

class NetworkConnectionStateNotifier
    extends StateNotifier<NetworkConnectionState> {
  NetworkConnectionStateNotifier(super.state);

  setNetworkStateByConnectivityResult(ConnectivityResult connectivityResult) {
    var onlineStates = <ConnectivityResult>[
      ConnectivityResult.wifi,
      ConnectivityResult.ethernet,
      ConnectivityResult.mobile
    ];

    var isOnlineState = onlineStates.contains(connectivityResult);

    state = isOnlineState
        ? NetworkConnectionState.online
        : NetworkConnectionState.offline;
  }
}

final networkConnectionStateProvider = StateNotifierProvider<
    NetworkConnectionStateNotifier, NetworkConnectionState>(
  (ref) => NetworkConnectionStateNotifier(NetworkConnectionState.offline),
);

And an enum:

enum NetworkConnectionState {
  offline,
  online
}

And the connectivity_plus package with a single event bootstrap statement:

@override
void initState() {
   super.initState();
   ...
   subscription = Connectivity()
        .onConnectivityChanged
        .listen((ConnectivityResult connectivityResult) {
      ref
          .read(networkConnectionStateProvider.notifier)
          .setNetworkStateByConnectivityResult(connectivityResult);
    });
}

XP

Test First Help to Improve and Simplify the Design

My sketched initial design was this:

It felt right to wrap the package calls with a service that could be overridden in test.

But when I started to code the bootstrapping and steps in the feature tests it got complex, especially given that GetConnectivity() method was an async future, it quickly felt like a code smell, bad, over complex code.

On top of that I realised that I didn’t need to use the new ConnectivityServiceProvider in the ‘_PrologueApp_’ widget.

Instead, I could simply listen to a connectivity change event via the package and just call the NetworkStateProvider and let it decide whether it was on or offline based on the ConnectivityResult.