Add solution sheet9

aufgaben/sheet9/sol2/fmt.rs

@@ -0,0 +1,42 @@
+struct LoveMachine<T> {
+    inner: T,
+}
+
+impl<T> LoveMachine<T> {
+    pub fn new(t: T) -> Self {
+        LoveMachine {
+            inner: t,
+        }
+    }
+}
+
+macro_rules! impl_fmt {
+    ($fmt_trait:ident, $fmt_str:expr) => {
+        impl<T> ::std::fmt::$fmt_trait for LoveMachine<T>
+            where T: ::std::fmt::$fmt_trait
+        {
+            fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+                write!(f, concat!("♥", $fmt_str, "♥"), self.inner)
+            }
+        }
+    }
+}
+
+impl_fmt!(Display,  "{}");
+impl_fmt!(Debug,    "{:?}");
+impl_fmt!(Octal,    "{:o}");
+impl_fmt!(LowerHex, "{:x}");
+impl_fmt!(UpperHex, "{:X}");
+impl_fmt!(Binary,   "{:b}");
+impl_fmt!(LowerExp, "{:e}");
+impl_fmt!(UpperExp, "{:E}");
+
+fn main() {
+    let lm = LoveMachine::new(27);
+    println!("Display:   {}", lm);
+    println!("Debug:     {:?}", lm);
+    println!("Octal:     {:o}", lm);
+    println!("LowerHex:  {:x}", lm);
+    println!("UpperHex:  {:X}", lm);
+    println!("Binary:    {:b}", lm);
+}