Deprecate publicly-visible properties on Style in path.

pkg/path/lib/src/context.dart

Index: pkg/path/lib/src/context.dart
diff --git a/pkg/path/lib/src/context.dart b/pkg/path/lib/src/context.dart
index 88ca61fa5eee43d2478fd5f68616c3261d55fd0f..f3826d78c6c307fe23c84184aea9f22e7b7751f2 100644
--- a/pkg/path/lib/src/context.dart
+++ b/pkg/path/lib/src/context.dart
@@ -4,6 +4,7 @@
 
 library path.context;
 
+import 'internal_style.dart';
 import 'style.dart';
 import 'parsed_path.dart';
 import 'path_exception.dart';
@@ -30,7 +31,12 @@ class Context {
       }
     }
 
-    if (style == null) style = Style.platform;
+    if (style == null) {
+      style = Style.platform;
+    } else if (style is! InternalStyle) {
+      throw new ArgumentError("Only styles defined by the path package are "
+          "allowed.");

[Bob Nystrom, 2014/05/29 15:45:39]

This is a breaking change, I think.

One option would to have the path package sniff out whether the Style passed in
is an InternalStyle or not. If it is, we can use the new faster parsing logic.
Otherwise, we can fall back to the old RegExp behavior.

Then, in 2.0.0, we remove support for the old behavior.

[nweiz, 2014/05/29 20:17:00]

This could technically break someone, but as you mentioned, I don't think any
user-defined styles exist in the wild. There's some leeway in versioning
packages for theoretically-but-not-practically breaking changes like adding a
top-level definition; I don't think it's worth bifurcating the Context and
ParsedPath classes to support a use case that no one will ever care about.

[Bob Nystrom, 2014/05/29 23:54:10]

If we don't think this will break anyone, then we aren't supporting user-defined
styles at all.

Given that, why have a deprecation period at all? Why not just yank the stuff
out now?

[nweiz, 2014/05/30 00:52:14]

Because it's (somewhat) plausible that people are calling
`path.platform.style.rootPattern` et al.

+    }
 
     return new Context._(style, current);
   }
@@ -38,7 +44,7 @@ class Context {
   Context._(this.style, this.current);
 
   /// The style of path that this context works with.
-  final Style style;
+  final InternalStyle style;
 
   /// The current directory that relative paths will be relative to.
   final String current;