Add logging function callback

engine/source/callback.d

@@ -0,0 +1,5 @@
+module gameengine.callback;
+
+import gameengine.logging.types;
+
+alias LoggerCallback = void function(LoggingSeverity severity, string message);

engine/source/core/engine.d

@@ -2,6 +2,8 @@ module gameengine.core.engine;
 
 import gameengine.graphics.drawable;
 import gameengine.renderer.renderer;
+import gameengine.logging.types;
+import gameengine.callback;
 import gameengine.node.node;
 import std.datetime.stopwatch;
 
@@ -9,12 +11,14 @@ import std.stdio;
 import std.format;
 
 class Engine {
-	this(Renderer renderer) {
+	this(Renderer renderer, LoggerCallback logger) {
 		this.renderer = renderer;
+		this.loggerCallback = logger;
 		previousProcessTick = 0.00001f;
 		previousPhysicsProcessTick = 0.00001f;
 
 		watch.start();
+		this.loggerCallback(LoggingSeverity.Information, "Started ge!");
 	}
 
 	~this() {
@@ -59,4 +63,5 @@ class Engine {
 	private float previousPhysicsProcessTick;
 
 	private Node*[] nodeList;
+	private LoggerCallback loggerCallback;
 }

engine/source/logging/types.d

@@ -0,0 +1,9 @@
+module gameengine.logging.types;
+
+enum LoggingSeverity {
+	Message = 0,
+	Information,
+	Warning,
+	Error,
+	Fatal
+}

test/source/app.d

@@ -1,15 +1,23 @@
 import std.stdio;
+import std.format;
+import std.conv;
 
 import gameengine.core.engine;
 import gameengine.math.types;
 import gameengine.renderer.renderer;
+import gameengine.logging.types;
+import gameengine.callback;
 import gameengine_rsdl;
 
 import core.thread;
 
+void logger(LoggingSeverity severity, string message) {
+	writeln(format("[%s]: %s", to!string(severity), message));
+}
+
 void main() {
 	Renderer renderer = new RSDL("test", IntVec2(800, 600));
-	Engine engine = new Engine(renderer);
+	Engine engine = new Engine(renderer, &logger);
 
 	ubyte red = 0;
 	bool increase = true;