/** * Poodinis Dependency Injection Framework * Copyright 2014-2021 Mike Bierlee * This software is licensed under the terms of the MIT license. * The full terms of the license can be found in the LICENSE file. */ import std.stdio; class Scheduler { private Calendar calendar; // All parameters will autmatically be assigned when Scheduler is created. this(Calendar calendar) { this.calendar = calendar; } public void scheduleJob() { calendar.findOpenDate(); } } class Calendar { private HardwareClock hardwareClock; // This constructor contains built-in type "int" and thus will not be used. this(int initialDateTimeStamp, HardwareClock hardwareClock) { } // This constructor is chosen instead as candidate for injection when Calendar is created. this(HardwareClock hardwareClock) { this.hardwareClock = hardwareClock; } public void findOpenDate() { hardwareClock.doThings(); } } class HardwareClock { // Parameterless constructors will halt any further selection of constructors. this() {} // As a result, this constructor will not be used when HardwareClock is created. this(Calendar calendar) { throw new Exception("This constructor should not be used by Poodinis"); } public void doThings() { writeln("Things are being done!"); } } void main() { import poodinis; // Locally imported to emphasize that classes do not depend on Poodinis. auto dependencies = new shared DependencyContainer(); dependencies.register!Scheduler; dependencies.register!Calendar; dependencies.register!HardwareClock; auto scheduler = dependencies.resolve!Scheduler; scheduler.scheduleJob(); }