add a comment to the generated lock file

utils/pub/lock_file.dart

Index: utils/pub/lock_file.dart
===================================================================
--- utils/pub/lock_file.dart	(revision 17925)
+++ utils/pub/lock_file.dart	(working copy)
@@ -13,6 +13,10 @@
 
 /// A parsed and validated `pubspec.lock` file.
 class LockFile {
+  
+  /// comment to append at start of lock file 
+  static final comment = "# Generated by pub. See: http://pub.dartlang.org/doc/glossary.html#lockfile";

[Bob Nystrom, 2013/01/31 22:17:44]

It's probably not worth making a constant for this. I'd just put the string
inline below.

[keertip, 2013/01/31 22:40:41]

Done.

+  
   /// The packages this lockfile pins.
   Map<String, PackageId> packages;
 
@@ -26,9 +30,9 @@
     var packages = <String, PackageId>{};
 
     if (contents.trim() == '') return new LockFile.empty();
+    // remove comment before parsing
+    var parsed = loadYaml(contents.replaceAll(comment, ''));

[Bob Nystrom, 2013/01/31 22:17:44]

This shouldn't be necessary. YAML supports comments and should ignore them
automatically.

[keertip, 2013/01/31 22:40:41]

Removed.

On 2013/01/31 22:17:44, Bob Nystrom wrote:

 
-    var parsed = loadYaml(contents);
-
     if (parsed.containsKey('packages')) {
       var packageEntries = parsed['packages'];
 
@@ -85,6 +89,7 @@
 
     // TODO(nweiz): Serialize using the YAML library once it supports
     // serialization. For now, we use JSON, since it's a subset of YAML anyway.
-    return json.stringify({'packages': packagesObj});
+    var lockFileString = json.stringify({'packages': packagesObj});
+    return '$comment $lockFileString';

[Bob Nystrom, 2013/01/31 22:17:44]

I'd use a multiline string here:

return '''
# Generated by pub...
${json.stringify({'packages': packagesObj})}
''';

[keertip, 2013/01/31 22:40:41]

Done.

   }
 }