Add example on constructor injection

.travis.yml

@@ -22,4 +22,5 @@ script:
   - dub build --build=release --config=annotationsExample
   - dub build --build=release --config=applicationContextExample
   - dub build --build=release --config=registerOnResolveExample
+  - dub build --build=release --config=constructorInjectionExample
 # - dub build --build=ddox

dub.json

@@ -102,6 +102,18 @@
 			"importPaths": [
 				"source"
 			]
+		},
+		{
+			"name" : "constructorInjectionExample",
+			"description" : "Example where dependencies are injected into constructors when their classes are created.",
+			"targetType": "executable",
+			"targetName": "constructorInjectionExample",
+			"sourcePaths": [
+				"example/constructorinjection"
+			],
+			"importPaths": [
+				"source"
+			]
 		}
 	]
 }

example/constructorinjection/app.d

@@ -0,0 +1,64 @@
+/**
+ * Poodinis Dependency Injection Framework
+ * Copyright 2014-2016 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.
+ */
+
+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() {
+		import std.stdio;
+		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();
+}