Use ByteArray's native for Socket and File.

runtime/lib/byte_array.dart

Index: runtime/lib/byte_array.dart
===================================================================
--- runtime/lib/byte_array.dart	(revision 3698)
+++ runtime/lib/byte_array.dart	(working copy)
@@ -96,6 +96,10 @@
   }
 
   void operator[]=(int index, int value) {
+    if (value is! int || !(value >= 0 && value <= 255)) {

[cshapiro, 2012/01/31 03:04:29]

Why not simplify this expression?

  if ((value is int) && (value >= 0) && (value <= 256)) {
    // set
  } else {
    // throw
  }

[Anders Johnsen, 2012/01/31 03:34:56]

Done.

+      throw const IllegalArgumentException(
+          "value is not an integer in byte range");
+    }
     setUint8(index, value);
   }
 
@@ -141,9 +145,36 @@
     return this[length - 1];
   }
 
+  void setRange(int start, int length, List<int> from, [int startFrom = 0]) {
+    if (length < 0) {
+      throw new IllegalArgumentException("negative length $length");
+    }
+    if (from is ByteArray) {
+      _setRange(from, startFrom, start, length);
+    } else {
+      Arrays.copy(from, startFrom, this, start, length);
+    }
+  }
+  
+  List getRange(int start, int length) {
+    if (length == 0) return [];
+    Arrays.rangeCheck(this, start, length);
+    ByteArray list = new ByteArray(length);
+    list._setRange(this, start, 0, length);
+    return list;
+  }
+
+
   // Implementation
 
   int _length() native "ByteArray_getLength";
+
+  void _setRange(ByteArray src,
+                 int srcStart,
+                 int dstStart,
+                 int count)
+      native "ByteArray_setRange";
+
 }