Add default formatters for Au and Range

src/components/util/geometry.rs

@@ -7,6 +7,7 @@ use geom::rect::Rect;
 use geom::size::Size2D;
 
 use std::num::{NumCast, One, Zero};
+use std::fmt;
 
 pub struct Au(i32);
 
@@ -18,6 +19,12 @@ impl Clone for Au {
     }
 }
 
+impl fmt::Default for Au {
+    fn fmt(obj: &Au, f: &mut fmt::Formatter) {
+        write!(f.buf, "Au({})", *obj);
+    }
+}
+
 impl Eq for Au {
     #[inline]
     fn eq(&self, other: &Au) -> bool {

src/components/util/range.rs

@@ -4,6 +4,7 @@
 
 use std::cmp::{max, min};
 use std::iter;
+use std::fmt;
 
 enum RangeRelation {
     OverlapsBegin(/* overlap */ uint),
@@ -21,6 +22,12 @@ pub struct Range {
     priv len: uint
 }
 
+impl fmt::Default for Range {
+    fn fmt(obj: &Range, f: &mut fmt::Formatter) {
+        write!(f.buf, "[{} .. {})", obj.begin(), obj.end());
+    }
+}
+
 impl Range {
     #[inline]
     pub fn new(off: uint, len: uint) -> Range {