DDC fixes for path

lib/src/context.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library path.context;
 
 import 'internal_style.dart';
 import 'style.dart';
 import 'parsed_path.dart';
 import 'path_exception.dart';
@@ skipping 22 matching lines @@
       }
     }
 
     if (style == null) {
       style = Style.platform;
     } else if (style is! InternalStyle) {
       throw new ArgumentError("Only styles defined by the path package are "
           "allowed.");
     }
 
     return new Context._(style, current);

[vsm, 2015/03/26 19:33:31]

Note, we get an implicit down cast warning on style here (to InternalStyle).  It
will always succeed though.

[Bob Nystrom, 2015/03/27 20:23:13]

Interesting. I'd be fine with explicit downcasting here. It's notable that this
is one of the known more odd corners of the path public API. We take in a public
type and require it to be an internal subclass.

So it's nice that ddc draws our attention to it.

[vsm, 2015/03/27 21:42:51]

Done.

   }
 
   /// Create a [Context] to be used internally within path.
   Context._internal()
       : style = Style.platform,

[vsm, 2015/03/26 19:33:31]

Ditto as Style.platform is typed to return a Style, not an InternalStyle.

[vsm, 2015/03/27 21:42:51]

Added explicit cast.

         _current = null;
 
   Context._(this.style, this._current);
 
   /// The style of path that this context works with.
   final InternalStyle style;
 
   /// The current directory given when Context was created. If null, current
   /// directory is evaluated from 'p.current'.
   final String _current;
@@ skipping 131 matching lines @@
   /// be added:
   ///
   ///     context.join('path/', 'to', 'foo'); // -> 'path/to/foo
   ///
   /// If a part is an absolute path, then anything before that will be ignored:
   ///
   ///     context.join('path', '/to', 'foo'); // -> '/to/foo'
   ///
   String join(String part1, [String part2, String part3, String part4,
       String part5, String part6, String part7, String part8]) {
-    var parts = [part1, part2, part3, part4, part5, part6, part7, part8];
+    var parts = <String>[part1, part2, part3, part4, part5, part6, part7, part8];

[vsm, 2015/03/26 19:33:31]

Note: 
  List<String> parts = [ ... ]
would work as well here and elsewhere.

[Bob Nystrom, 2015/03/27 20:24:04]

I prefer how you did this.

     _validateArgList("join", parts);
     return joinAll(parts.where((part) => part != null));
   }
 
   /// Joins the given path parts into a single path. Example:
   ///
   ///     context.joinAll(['path', 'to', 'foo']); // -> 'path/to/foo'
   ///
   /// If any part ends in a path separator, then a redundant separator will not
   /// be added:
@@ skipping 345 matching lines @@
     var message = new StringBuffer();
     message.write("$method(");
     message.write(args
         .take(numArgs)
         .map((arg) => arg == null ? "null" : '"$arg"')
         .join(", "));
     message.write("): part ${i - 1} was null, but part $i was not.");
     throw new ArgumentError(message.toString());
   }
 }