How to initialize a static variable and set various value for it?-CodePudding

In java, if you want to initialize a static variable once, you can write code in Static Initialization Block just like this:

abstract class Dummy {
    static final Map<String, object> cache = new HashMap();

    static {
        cache.add('foo', new Foo());
        cache.add('bar', new Bar());
    }
}

Here I want to ask if there have a similar way in Dart? What is the best coding practice in Dart programming?

abstract class Dummy {
  static final Map<String, dynamic> cache = <String, dynamic>{};
}

CodePudding user response：

Well, there is no static initialization block in dart, but there are some other approaches you could take here.

Firstly, if all you want to do is add a few items to a map, you can just use map literal syntax:

abstract class Dummy {
  static final Map<String, dynamic> cache = <String, dynamic>{
    'foo': Foo(),
    'bar': Bar(),
  };
}

Also if you just want to initialize a static value by calling a few methods on it, you can use cascade notation .., which for this specific example would look like this:

abstract class Dummy {
  static final Map<String, dynamic> cache = <String, dynamic>{}
    ..['foo'] = Foo()
    ..['bar'] = Bar();
}

The above is using cascade to call the []= operator on the map instance, but you can call any method on the map instance using cascade. For example, I could also call the remove method:

abstract class Dummy {
  static final Map<String, dynamic> cache = <String, dynamic>{}
    ..['foo'] = Foo()
    ..['bar'] = Bar()
    ..remove('foo');
}