Dependencies

In this section, we will explain how dependency management is handled by the framework. This is a very important feature, especially in case of big projects in which you will have to split your source code in several files.

ES6 modules#

Dana uses the Javascript ES6 modules notation to load classes and configuration files for the application.

A class is declared in a module as follows:

import $Class from "@Class";

export default $Class.declare("MyClass", { /* class def */ });

Aliases#

The framework provides class names and class constructors aliases for all framework classes. This mechanism allows to move classes to different packages without any impact on the application side.

There are two different kinds of aliases:

• _Class which is referencing the fully qualified name of a Class.
• $Class as a reference to the Class constructor from which you can create instance.

Injection#

The framework comes with a dependency injection (DI) mechanism where the implementation of components used in the application, are resolved by the configuration. A Component declares an abstract class or an abstract model that must be implemented. For a component, there may be multiple implementations. You never need to import a specific implementation (otherwise, you need to import the component by its name and the tooling will inject the right implementation depending on your configuration).

First, you need to declare your component like this:

import $Abstract from "@Abstract";
/**
 * @component
 */
export default $Abstract.declare("AbstractSearch", {
    search: function() {
       return this._search();
    },
    /**
     * @abstract
     */
    _search: function() {
       return this._notImplementedPromise("_search");
    }
);

Then, here is a typical implementation of the component:

import $AbstractSearch from "@AbstractSearch";
/**
 * @implementation
 */
export default $AbstractSearch.declare("DefaultSearch", {
    /**
     * @override
     */
    _search: function() {
       // do your implementation !
    }
);

And finally, you can use the “Search” component in your application:

import $Search from "@Search";

// $Search will be resolved to right implementation
// In this example, $Search === $DefaultSearch

);