Show better error messages in network failures.

utils/pub/hosted_source.dart

 // Copyright (c) 2012, 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 hosted_source;
 
 import 'dart:io' as io;
 import 'dart:json';
 import 'dart:uri';
 
@@ skipping 23 matching lines @@
    * site.
    */
   Future<List<Version>> getVersions(String name, description) {
     var parsed = _parseDescription(description);
     var fullUrl = "${parsed.last}/packages/${parsed.first}.json";
 
     return httpGetString(fullUrl).transform((body) {
       var doc = JSON.parse(body);
       return doc['versions'].map((version) => new Version.parse(version));
     }).transformException((ex) {
-      if (ex is PubHttpException && ex.statusCode == 404) {
-        throw 'Could not find package "${parsed.first}" on ${parsed.last}.';
-      }
-
-      // Otherwise re-throw the original exception.
-      throw ex;
+      _throwFriendlyError(ex, parsed.first, parsed.last);
     });
   }
 
   /**
    * Downloads and parses the pubspec for a specific version of a package that
    * is available from the site.
    */
   Future<Pubspec> describe(PackageId id) {
     var parsed = _parseDescription(id.description);
     var fullUrl = "${parsed.last}/packages/${parsed.first}/versions/"
       "${id.version}.yaml";
+
     return httpGetString(fullUrl).transform((yaml) {
       return new Pubspec.parse(yaml, systemCache.sources);
+    }).transformException((ex) {
+      _throwFriendlyError(ex, id, parsed.last);
     });
   }
 
   /**
    * Downloads a package from the site and unpacks it.
    */
   Future<bool> install(PackageId id, String destPath) {
     var parsedDescription = _parseDescription(id.description);
     var name = parsedDescription.first;
     var url = parsedDescription.last;
@@ skipping 41 matching lines @@
    * Ensures that [description] is a valid hosted package description.
    *
    * There are two valid formats. A plain string refers to a package with the
    * given name from the default host, while a map with keys "name" and "url"
    * refers to a package with the given name from the host at the given URL.
    */
   void validateDescription(description, {bool fromLockFile: false}) {
     _parseDescription(description);
   }
 
+  /// When an error occurs trying to read something about [package] from [url],
+  /// this tries to translate into a more user friendly error message. Always
+  /// throws an error, either the original one or a better one.
+  void _throwFriendlyError(ex, package, url) {
+    if (ex is PubHttpException && ex.statusCode == 404) {
+      throw 'Could not find package "${package}" at ${url}.';

[nweiz, 2012/11/05 19:55:36]

Why "${package}" and "${url}" over "$package" and "$url"?

[Bob Nystrom, 2012/11/05 20:43:06]

Done. There used to be more complex expressions in there, and I didn't remember
to ditch the curlies when I simplified them.

+    }
+
+    if (ex is TimeoutException) {
+      throw 'Timed out trying to find package "${package}" at ${url}.';
+    }
+
+    if (ex is io.SocketIOException) {
+      throw 'Got socket error trying to find package "${package}" at ${url}.\n'
+          '${ex.osError}';
+    }
+
+    // Otherwise re-throw the original exception.
+    throw ex;
+  }
+
   /**
    * Parses the description for a package.
    *
    * If the package parses correctly, this returns a (name, url) pair. If not,
    * this throws a descriptive FormatException.
    */
   Pair<String, String> _parseDescription(description) {
     if (description is String) {
       return new Pair<String, String>(description, defaultUrl);
     }
@@ skipping 10 matching lines @@
 
     var name = description["name"];
     if (name is! String) {
       throw new FormatException("The 'name' key must have a string value.");
     }
 
     var url = description.containsKey("url") ? description["url"] : defaultUrl;
     return new Pair<String, String>(name, url);
   }
 }