add section about exceptions

hands-on_dlang.md

@@ -71,6 +71,8 @@
             - [Functions as arguments](#functions-as-arguments)
             - [Local functions with context](#local-functions-with-context)
             - [Anonymous functions and lambdas](#anonymous-functions-and-lambdas)
+        - [Exceptions](#exceptions)
+            - [`nothrow`](#nothrow)
 
 ## Setup
 
@@ -1062,3 +1064,46 @@ These are often passed as template arguments in the functional parts of Phobos:
 ```D
 [1, 2, 3].reduce!((a, b) => a + b)();
 ```
+
+### Exceptions
+Exceptions in D are very similar to Exceptions in Java:
+
+```D
+class MyException : Exception {
+    this(string msg) {
+        super("MyException was thrown because of " ~ msg);
+    }
+}
+
+try {
+    throw new MyException("no reason");
+}
+catch (FileException e) { // not caught here
+    /* … */
+}
+catch (MyException e) { // but here
+    /* … */
+}
+finally { // executed regardless of whether an exception was thrown or not
+    /* … */
+}
+```
+
+#### `nothrow`
+
+The compiler can enforce that a function can not throw an exception. You can
+achieve this by annotating a function with `nothrow`:
+
+```D
+import std.exception: enforce; // convenience function which throws if `false` is passed
+
+int divide(int a, int b) {
+    enforce(b != 0, "Can't divide by 0!");
+    return a / b;
+}
+
+int divide4By2() nothrow {
+    return divide(4, 2); // error, divide my throw
+}
+
+```