Pass in "mode" to transformer plugins.

pkg/barback/lib/src/barback_settings.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 barback.barback_settings;
+
+/// A generic settings object for providing configuration details to
+/// [Transformer]s.
+///
+/// Barback does not specify *how* this is provided to transformers. It is up
+/// to a host application to handle this. (For example, pub passes this to the
+/// transformer's constructor.)
+class BarbackSettings {
+  /// An open-ended map of configuration properties specific to this
+  /// transformer.
+  ///
+  /// Aside from requiring to be serializable across isolates, Barback places

[nweiz, 2013/10/31 00:24:41]

"requiring to be" -> "requiring that this be" or "requiring this to be"

Also, technically it's pub that requires this to be serializable. I don't know
if that's a distinction worth making here, though.

[Bob Nystrom, 2013/10/31 01:51:19]

Reworded.

+  /// no restrictions on what this should contain.
+  final Map transformer;

[nweiz, 2013/10/31 00:24:41]

I agree with Siggi that this reads awkwardly. What about [forTransformer]?

[Bob Nystrom, 2013/10/31 01:51:19]

I think that's worse. I can do "transformerConfiguration", but that's a
mouthful.

[nweiz, 2013/10/31 18:47:56]

"fromUser"? "fromPubspec"? "pubspec"?

"transformer" really sounds like it's going to return the transformer, or some
information about the transformer. "transformerConfiguration" would be better,
but it's really awfully verbose.

[Bob Nystrom, 2013/10/31 20:04:08]

Changed to "configuration".

+
+  /// The overall development mode that user is running Barback in. This will

[nweiz, 2013/10/31 00:24:41]

Paragraph break.

"development mode" is confusing since "development" is often used as the name of
such a mode. Maybe just remove "development"?

[Bob Nystrom, 2013/10/31 01:51:19]

Removed "overall" too.

+  /// be the same for all transformers in a running instance of Barback.
+  final BarbackMode mode;
+
+  BarbackSettings(this.transformer, this.mode);
+}
+
+/// Enum-like class for specifying a mode that transformers may be run in.
+///
+/// Note that this is not a *closed* set of enum values. Host applications may
+/// define their own values for this, so a transformer relying on it should
+/// ensure that it behaves sanely with unknown values.
+class BarbackMode {
+  /// The normal mode used during development.
+  static const DEBUG = const BarbackMode("debug");
+
+  /// The normal mode used to build an application for deploying to production.
+  static const RELEASE = const BarbackMode("release");
+
+  /// The name of the mode.
+  ///
+  /// By convention, this is a lowercase string.
+  final String name;
+
+  const BarbackMode(this.name);
+
+  /// Create a mode named [name].
+  factory BarbackMode.fromString(String name) {

[nweiz, 2013/10/31 00:24:41]

It's confusing for this to be a different constructor than [new BarbackMode].
Isn't the other one constructing the mode from a string as well? I'd make this
the default constructor and rename what is now [new BarbackMode] to [new
BarbackMode._].

[Bob Nystrom, 2013/10/31 01:51:19]

Done. Not sure what I was thinking here.

+    // Use canonical instances of known names.
+    switch (name) {
+      case "debug": return BarbackMode.DEBUG;
+      case "release": return BarbackMode.RELEASE;
+      default:
+        return new BarbackMode(name);
+    }
+  }
+
+  String toString() => name;
+}