tiny_locator 1.0.0+2

Tiny service locator that provides a global access point to services.

tiny_locator

English, 日本語

Tiny service locator that provides a global access point to services.
It can be combined with tiny_react to make a tiny state management library in Flutter.

It is a very small library with less than 100 lines (without comments), so it is easy for anyone to understand how it works.

Features

• Lookup services
• Hierarchical scopes

As the name suggests, smallness is our selling point, so we don't plan to add major features in the future, but we may add features that require only small fixes.

Getting started

The simplest way to use it is as follows.

import 'package:tiny_locator/tiny_locator.dart';
void main() {
  // register
  locator.add(() => 'abc');
  // lookup
  print(locator.get<String>());
}

The ServiceLocator class is a singleton, and the object is assigned to the global variable locator in advance.

Usage

Register with singleton

Creates and registers the only object immediately. Retrieving it with get will return the same object.

locator.add(() => Controller());

Register as delayed creation

The object will be created at the time of acquisition with get. After that, the same object will be retrieved.

locator.add(() => Controller(), lazy: true);

Register as created every time

A new object will be created each time it is retrieved with get.

locator.add(() => Controller(), singleton: false);

Register as tagged

If you register the same class, it will be overwritten. If you want to register it as a different one, add tag.

locator.add(() => Controller(), tag: 'abc');

Lookup

The service is retrieved by specifying the type and tag. If the service is not registered, an exception will be raised. You can also use contains to get whether a service is registered or not.

if (locator.contains<Controller>()) {
  locator.get<Controller>();
}
if (locator.contains<Controller>(tag: 'abc')) {
  locator.get<Controller>(tag: 'abc');
}

Remove

It can also be deleted as well as get.

if (locator.remove<Controller>()) {
  print('deleted');
};
locator.remove<Controller>(tag: 'abc');

Scope

The ServiceLocator class retains the ServiceContainer, an implementation of the ServiceLocator, in a hierarchical structure.
You can use pop and push to add and remove ServiceContainer from the hierarchy and use it as a scope.
It is mainly intended to be used with Flutter's Navigator.

// register in the root scope
locator.add(() => ClassA());
// create a new scope
locator.push();
// register in a new scope
locator.add(() => ClassB());
// you can find both ClassA and ClassB
locator.get<ClassA>();
locator.get<ClassB>();
// destroy the current scope
locator.pop();
// now, you can find only ClassA
locator.get<ClassA>();
locator.get<ClassB>(); // Exception!

tiny_react

tiny_react is a syntax sugar to ValueNotifier and ValueListenableBuilder.
When combined with tiny_locator, it becomes Flutter's tiny state management method.

import 'package:flutter/material.dart';
import 'package:tiny_locator/tiny_locator.dart';
import 'package:tiny_react/tiny_react.dart';

class MyController {
  final num = 0.notif;
  final list = <int>[].notif;

  void doSomething() {
    num.value++;
    if (num.value % 2 == 0) {
      list
        ..value.add(num.value)
        ..notifyListeners();
    }
  }
}

void main() {
  locator.add(() => MyController());
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: MyPage(),
    );
  }
}

class MyPage extends StatelessWidget {
  final controller = locator.get<MyController>();

  MyPage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('MyPage')),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            const Text(
              'You have pushed the button this many times:',
            ),
            controller.num.build((val) => Text('$val')),
            controller.list.build((val) => Text('$val')),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () => controller.doSomething(),
        child: const Icon(Icons.add),
      ),
    );
  }
}