no longer require entry points to be specified in the build.dart file

pkg/polymer/lib/builder.dart

Index: pkg/polymer/lib/builder.dart
diff --git a/pkg/polymer/lib/builder.dart b/pkg/polymer/lib/builder.dart
index a2eb80fe467c3650be771424b07168ece67e90f2..e85217d1fea7454757068407844416a014c60ff0 100644
--- a/pkg/polymer/lib/builder.dart
+++ b/pkg/polymer/lib/builder.dart
@@ -83,6 +83,7 @@ import 'dart:async';
 import 'dart:io';
 
 import 'package:args/args.dart';
+import 'package:yaml/yaml.dart';
 
 import 'src/build/linter.dart';
 import 'src/build/runner.dart';
@@ -116,6 +117,8 @@ Future build({List<String> entryPoints, CommandLineOptions options,
         ' options to build(). Running as if no options were passed.');
     options = parseOptions([]);
   }
+  if (entryPoints == null) entryPoints = _parseEntryPointsFromPubspec();
+
   return options.forceDeploy
       ? deploy(entryPoints: entryPoints, options: options,
             currentPackage: currentPackage, packageDirs: packageDirs)
@@ -145,8 +148,10 @@ Future lint({List<String> entryPoints, CommandLineOptions options,
     options = parseOptions([]);
   }
   if (currentPackage == null) currentPackage = readCurrentPackageFromPubspec();
+  if (entryPoints == null) entryPoints = _parseEntryPointsFromPubspec();
   var linterOptions = new TransformOptions(entryPoints: entryPoints);
   var linter = new Linter(linterOptions);
+
   return runBarback(new BarbackOptions([[linter]], null,
       currentPackage: currentPackage, packageDirs: packageDirs,
       machineFormat: options.machineFormat));
@@ -177,6 +182,7 @@ Future deploy({List<String> entryPoints, CommandLineOptions options,
     options = parseOptions([]);
   }
   if (currentPackage == null) currentPackage = readCurrentPackageFromPubspec();
+  if (entryPoints == null) entryPoints = _parseEntryPointsFromPubspec();
 
   var transformOptions = new TransformOptions(
       entryPoints: entryPoints,
@@ -318,3 +324,39 @@ CommandLineOptions parseOptions([List<String> args]) {
       res['full'], res['machine'], res['deploy'], res['out'], res['js'],
       res['csp'], !res['debug']);
 }
+
+List<String> _parseEntryPointsFromPubspec() {
+  var entryPoints = [];
+  var pubspec = new File('pubspec.yaml');
+  if (!pubspec.existsSync()) {

[Siggi Cherem (dart-lang), 2014/09/15 21:35:20]

one option here - instead of using the CWD, use the script path:

path.join(
  path.dirname(Platform.script.path),
  'pubspec.yaml')

[jakemac, 2014/09/15 22:20:51]

Done.

+    print('error: pubspec.yaml file not found, please run this script from '
+          'your package root directory.');
+    return entryPoints;
+  }
+  var transformers = loadYaml(pubspec.readAsStringSync())['transformers'];
+  if (transformers == null) return entryPoints;
+  if (transformers is! List || transformers.any((t) => t is! Map)) {

[Siggi Cherem (dart-lang), 2014/09/15 21:35:20]

entries in the transformer can actually be strings too. For example,

transformers:
- polymer

is valid.

[jakemac, 2014/09/15 22:20:52]

Done.

+    print('Unexpected value for transformers, expected a List<Map>.');
+    return entryPoints;
+  }
+
+  transformers.forEach((t) {
+    var polymer = t['polymer'];
+    if (polymer == null) return;
+    var parsedEntryPoints = polymer['entry_points'];
+    if (parsedEntryPoints == null) return;
+
+    var error = false;
+    if (parsedEntryPoints is String) parsedEntryPoints = [parsedEntryPoints];
+    else if (parsedEntryPoints is! List) error = true;

[Siggi Cherem (dart-lang), 2014/09/15 21:35:20]

style nit: use { } in this and the previous line.

(we only use `if (x) something;` without '{ }' if it fits on a single line and
there is no else.)

[jakemac, 2014/09/15 22:20:52]

Done.

+    if (parsedEntryPoints.any((e) => e is! String)) error = true;

[Siggi Cherem (dart-lang), 2014/09/15 21:35:20]

actually - to avoid code duplication, you could just make the 'readEntrypoints'
function in transformer.dart public, and use it here

[jakemac, 2014/09/15 22:20:52]

Done.

+    if (error) {
+      print('Invalid value for "entry_points" in polymer transformer. Expected '
+            'a String or List<String>.');
+      return;
+    }
+
+    entryPoints.addAll(parsedEntryPoints);

[Siggi Cherem (dart-lang), 2014/09/15 21:35:20]

also return here? (once we find the polymer section, we should be done).

[jakemac, 2014/09/15 22:20:52]

Technically, it works to have multiple different polymer transformer sections. I
can't think of the specific use case off the top of my head but there is no
reason to prevent it.

On 2014/09/15 21:35:20, Siggi Cherem (dart-lang) wrote:

+  });
+  return entryPoints;
+}