About Concerns Available since v0.9

Inspired by PHP's Traits, traditional mixins, and a few concepts from dependency injection, the @aedart/support/concerns submodule offers an alternative approach to reducing some of the limitations of single inheritance.

In this context, a "concern" is a class that can be injected into a target class, by means of the use() class decorator. The public properties and methods of the concern class are then "aliased" into the target class' prototype. In other words, "proxy" properties and methods are defined in the target class. They forward any interaction to the original properties and methods in the concern class instance.

Example

import { use, AbstractConcern } from "@aedart/support/concerns";

// A concern class...
class ConsolePrinter extends AbstractConcern {
    print(message) {
        console.log(message);
    }
}

// Taget class that uses a concern...
@use(ConsolePrinter)
class Person {
    
    sayHi(name) {
        // Call method in concern
        this.print(`Hi ${name}`);
    }
}

// Later in your application...
const person = new Person();
person.sayHi('Atrid'); // Hi Astrid

person.print('Ho ho ho...'); // Ho ho ho...

See also "Real" mixins as an alternative.