Added the ability to use an IEnumerable<T> when adding to a list, so you can do:

new Foo.Builder {
   RepeatedValue = { x.Select(y) }
};

... a bit like LINQ to XML.

src/AddressBook/AddressBookProtos.cs

@@ -668,7 +668,7 @@ namespace Google.ProtocolBuffers.Examples.AddressBook {
         return this;
       }
       
-      public scg::IList<global::Google.ProtocolBuffers.Examples.AddressBook.Person.Types.PhoneNumber> PhoneList {
+      public pbc::IPopsicleList<global::Google.ProtocolBuffers.Examples.AddressBook.Person.Types.PhoneNumber> PhoneList {
         get { return result.phone_; }
       }
       public int PhoneCount {
@@ -910,7 +910,7 @@ namespace Google.ProtocolBuffers.Examples.AddressBook {
       }
       
       
-      public scg::IList<global::Google.ProtocolBuffers.Examples.AddressBook.Person> PersonList {
+      public pbc::IPopsicleList<global::Google.ProtocolBuffers.Examples.AddressBook.Person> PersonList {
         get { return result.person_; }
       }
       public int PersonCount {

src/ProtoGen/RepeatedEnumFieldGenerator.cs

@@ -29,7 +29,8 @@ namespace Google.ProtocolBuffers.ProtoGen {
 
     public void GenerateBuilderMembers(TextGenerator writer) {
       // Note:  We can return the original list here, because we make it unmodifiable when we build
-      writer.WriteLine("public scg::IList<{0}> {1}List {{", TypeName, PropertyName);
+      // We return it via IPopsicleList so that collection initializers work more pleasantly.
+      writer.WriteLine("public pbc::IPopsicleList<{0}> {1}List {{", TypeName, PropertyName);
       writer.WriteLine("  get {{ return result.{0}_; }}", Name);
       writer.WriteLine("}");
       writer.WriteLine("public int {0}Count {{", PropertyName);

src/ProtoGen/RepeatedMessageFieldGenerator.cs

@@ -28,7 +28,8 @@ namespace Google.ProtocolBuffers.ProtoGen {
 
     public void GenerateBuilderMembers(TextGenerator writer) {
       // Note:  We can return the original list here, because we make it unmodifiable when we build
-      writer.WriteLine("public scg::IList<{0}> {1}List {{", TypeName, PropertyName);
+      // We return it via IPopsicleList so that collection initializers work more pleasantly.
+      writer.WriteLine("public pbc::IPopsicleList<{0}> {1}List {{", TypeName, PropertyName);
       writer.WriteLine("  get {{ return result.{0}_; }}", Name);
       writer.WriteLine("}");
       writer.WriteLine("public int {0}Count {{", PropertyName);

src/ProtoGen/RepeatedPrimitiveFieldGenerator.cs

@@ -34,8 +34,9 @@ namespace Google.ProtocolBuffers.ProtoGen {
 
     public void GenerateBuilderMembers(TextGenerator writer) {
       // Note:  We can return the original list here, because we make it unmodifiable when we build
+      // We return it via IPopsicleList so that collection initializers work more pleasantly.
       AddClsComplianceCheck(writer);
-      writer.WriteLine("public scg::IList<{0}> {1}List {{", TypeName, PropertyName);
+      writer.WriteLine("public pbc::IPopsicleList<{0}> {1}List {{", TypeName, PropertyName);
       writer.WriteLine("  get {{ return result.{0}_; }}", Name);
       writer.WriteLine("}");
       writer.WriteLine("public int {0}Count {{", PropertyName);

src/ProtocolBuffers.Test/Collections/PopsicleListTest.cs

@@ -16,6 +16,7 @@ namespace Google.ProtocolBuffers.Collections {
       AssertNotSupported(() => list.Insert(0, ""));
       AssertNotSupported(() => list.Remove(""));
       AssertNotSupported(() => list.RemoveAt(0));
+      AssertNotSupported(() => list.Add(new[] {"", ""}));
     }
 
     [Test]

src/ProtocolBuffers.Test/GeneratedMessageTest.cs

@@ -34,6 +34,7 @@ using System.Collections.Generic;
 using Google.ProtocolBuffers.Descriptors;
 using Google.ProtocolBuffers.TestProtos;
 using NUnit.Framework;
+using Google.ProtocolBuffers.Collections;
 
 namespace Google.ProtocolBuffers {
   [TestFixture]
@@ -193,6 +194,22 @@ namespace Google.ProtocolBuffers {
       Assert.AreEqual(expectedMessage, message);
     }
 
+    [Test]
+    public void SettingRepeatedValuesUsingRangeInCollectionInitializer() {
+      int[] values = { 1, 2, 3 };
+      TestAllTypes message = new TestAllTypes.Builder {
+        RepeatedSint32List = { values }
+      }.Build();
+      Assert.IsTrue(Lists.Equals(values, message.RepeatedSint32List));
+    }
+
+    [Test]
+    public void SettingRepeatedValuesUsingIndividualValuesInCollectionInitializer() {
+      TestAllTypes message = new TestAllTypes.Builder {
+        RepeatedSint32List = { 6, 7 }
+      }.Build();
+      Assert.IsTrue(Lists.Equals(new int[] { 6, 7 }, message.RepeatedSint32List));
+    }
     
     [Test]
     public void Defaults() {

src/ProtocolBuffers.Test/TestProtos/UnitTestEmbedOptimizeForProtoFile.cs

@@ -321,7 +321,7 @@ namespace Google.ProtocolBuffers.TestProtos {
         return this;
       }
       
-      public scg::IList<global::Google.ProtocolBuffers.TestProtos.TestOptimizedForSize> RepeatedMessageList {
+      public pbc::IPopsicleList<global::Google.ProtocolBuffers.TestProtos.TestOptimizedForSize> RepeatedMessageList {
         get { return result.repeatedMessage_; }
       }
       public int RepeatedMessageCount {

src/ProtocolBuffers.Test/TestProtos/UnitTestMessageSetProtoFile.cs

@@ -1401,7 +1401,7 @@ namespace Google.ProtocolBuffers.TestProtos {
       }
       
       
-      public scg::IList<global::Google.ProtocolBuffers.TestProtos.RawMessageSet.Types.Item> ItemList {
+      public pbc::IPopsicleList<global::Google.ProtocolBuffers.TestProtos.RawMessageSet.Types.Item> ItemList {
         get { return result.item_; }
       }
       public int ItemCount {

src/ProtocolBuffers/Collections/IPopsicleList.cs

+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://github.com/jskeet/dotnet-protobufs/
+// Original C++/Java/Python code:
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+using System.Collections.Generic;
+
+namespace Google.ProtocolBuffers.Collections {
+  /// <summary>
+  /// A list which has an Add method which accepts an IEnumerable[T].
+  /// This allows whole collections to be added easily using collection initializers.
+  /// It causes a potential overload confusion if T : IEnumerable[T], but in
+  /// practice that won't happen in protocol buffers.
+  /// </summary>
+  /// <remarks>This is only currently implemented by PopsicleList, and it's likely
+  /// to stay that way - hence the name. More genuinely descriptive names are
+  /// horribly ugly. (At least, the ones the author could think of...)</remarks>
+  /// <typeparam name="T">The element type of the list</typeparam>
+  public interface IPopsicleList<T> : IList<T> {
+    void Add(IEnumerable<T> collection);
+  }
+}

src/ProtocolBuffers/Collections/PopsicleList.cs

@@ -39,7 +39,7 @@ namespace Google.ProtocolBuffers.Collections {
   /// to be made read-only (with the <see cref="MakeReadOnly" /> method), 
   /// after which any modifying methods throw <see cref="NotSupportedException" />.
   /// </summary>
-  public sealed class PopsicleList<T> : IList<T> {
+  public sealed class PopsicleList<T> : IPopsicleList<T> {
 
     private readonly List<T> items = new List<T>();
     private bool readOnly = false;
@@ -108,6 +108,13 @@ namespace Google.ProtocolBuffers.Collections {
       return items.Remove(item);
     }
 
+    public void Add(IEnumerable<T> collection) {
+      if (readOnly) {
+        throw new NotSupportedException("List is read-only");
+      }
+      items.AddRange(collection);
+    }
+
     public IEnumerator<T> GetEnumerator() {
       return items.GetEnumerator();
     }

src/ProtocolBuffers/DescriptorProtos/DescriptorProtoFile.cs

@@ -419,7 +419,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
       }
       
       
-      public scg::IList<global::Google.ProtocolBuffers.DescriptorProtos.FileDescriptorProto> FileList {
+      public pbc::IPopsicleList<global::Google.ProtocolBuffers.DescriptorProtos.FileDescriptorProto> FileList {
         get { return result.file_; }
       }
       public int FileCount {
@@ -902,7 +902,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return this;
       }
       
-      public scg::IList<string> DependencyList {
+      public pbc::IPopsicleList<string> DependencyList {
         get { return result.dependency_; }
       }
       public int DependencyCount {
@@ -930,7 +930,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return this;
       }
       
-      public scg::IList<global::Google.ProtocolBuffers.DescriptorProtos.DescriptorProto> MessageTypeList {
+      public pbc::IPopsicleList<global::Google.ProtocolBuffers.DescriptorProtos.DescriptorProto> MessageTypeList {
         get { return result.messageType_; }
       }
       public int MessageTypeCount {
@@ -968,7 +968,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return this;
       }
       
-      public scg::IList<global::Google.ProtocolBuffers.DescriptorProtos.EnumDescriptorProto> EnumTypeList {
+      public pbc::IPopsicleList<global::Google.ProtocolBuffers.DescriptorProtos.EnumDescriptorProto> EnumTypeList {
         get { return result.enumType_; }
       }
       public int EnumTypeCount {
@@ -1006,7 +1006,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return this;
       }
       
-      public scg::IList<global::Google.ProtocolBuffers.DescriptorProtos.ServiceDescriptorProto> ServiceList {
+      public pbc::IPopsicleList<global::Google.ProtocolBuffers.DescriptorProtos.ServiceDescriptorProto> ServiceList {
         get { return result.service_; }
       }
       public int ServiceCount {
@@ -1044,7 +1044,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return this;
       }
       
-      public scg::IList<global::Google.ProtocolBuffers.DescriptorProtos.FieldDescriptorProto> ExtensionList {
+      public pbc::IPopsicleList<global::Google.ProtocolBuffers.DescriptorProtos.FieldDescriptorProto> ExtensionList {
         get { return result.extension_; }
       }
       public int ExtensionCount {
@@ -1776,7 +1776,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return this;
       }
       
-      public scg::IList<global::Google.ProtocolBuffers.DescriptorProtos.FieldDescriptorProto> FieldList {
+      public pbc::IPopsicleList<global::Google.ProtocolBuffers.DescriptorProtos.FieldDescriptorProto> FieldList {
         get { return result.field_; }
       }
       public int FieldCount {
@@ -1814,7 +1814,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return this;
       }
       
-      public scg::IList<global::Google.ProtocolBuffers.DescriptorProtos.FieldDescriptorProto> ExtensionList {
+      public pbc::IPopsicleList<global::Google.ProtocolBuffers.DescriptorProtos.FieldDescriptorProto> ExtensionList {
         get { return result.extension_; }
       }
       public int ExtensionCount {
@@ -1852,7 +1852,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return this;
       }
       
-      public scg::IList<global::Google.ProtocolBuffers.DescriptorProtos.DescriptorProto> NestedTypeList {
+      public pbc::IPopsicleList<global::Google.ProtocolBuffers.DescriptorProtos.DescriptorProto> NestedTypeList {
         get { return result.nestedType_; }
       }
       public int NestedTypeCount {
@@ -1890,7 +1890,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return this;
       }
       
-      public scg::IList<global::Google.ProtocolBuffers.DescriptorProtos.EnumDescriptorProto> EnumTypeList {
+      public pbc::IPopsicleList<global::Google.ProtocolBuffers.DescriptorProtos.EnumDescriptorProto> EnumTypeList {
         get { return result.enumType_; }
       }
       public int EnumTypeCount {
@@ -1928,7 +1928,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return this;
       }
       
-      public scg::IList<global::Google.ProtocolBuffers.DescriptorProtos.DescriptorProto.Types.ExtensionRange> ExtensionRangeList {
+      public pbc::IPopsicleList<global::Google.ProtocolBuffers.DescriptorProtos.DescriptorProto.Types.ExtensionRange> ExtensionRangeList {
         get { return result.extensionRange_; }
       }
       public int ExtensionRangeCount {
@@ -2858,7 +2858,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return this;
       }
       
-      public scg::IList<global::Google.ProtocolBuffers.DescriptorProtos.EnumValueDescriptorProto> ValueList {
+      public pbc::IPopsicleList<global::Google.ProtocolBuffers.DescriptorProtos.EnumValueDescriptorProto> ValueList {
         get { return result.value_; }
       }
       public int ValueCount {
@@ -3532,7 +3532,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return this;
       }
       
-      public scg::IList<global::Google.ProtocolBuffers.DescriptorProtos.MethodDescriptorProto> MethodList {
+      public pbc::IPopsicleList<global::Google.ProtocolBuffers.DescriptorProtos.MethodDescriptorProto> MethodList {
         get { return result.method_; }
       }
       public int MethodCount {
@@ -4365,7 +4365,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return this;
       }
       
-      public scg::IList<global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption> UninterpretedOptionList {
+      public pbc::IPopsicleList<global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption> UninterpretedOptionList {
         get { return result.uninterpretedOption_; }
       }
       public int UninterpretedOptionCount {
@@ -4653,7 +4653,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return this;
       }
       
-      public scg::IList<global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption> UninterpretedOptionList {
+      public pbc::IPopsicleList<global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption> UninterpretedOptionList {
         get { return result.uninterpretedOption_; }
       }
       public int UninterpretedOptionCount {
@@ -5083,7 +5083,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return this;
       }
       
-      public scg::IList<global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption> UninterpretedOptionList {
+      public pbc::IPopsicleList<global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption> UninterpretedOptionList {
         get { return result.uninterpretedOption_; }
       }
       public int UninterpretedOptionCount {
@@ -5330,7 +5330,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
       }
       
       
-      public scg::IList<global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption> UninterpretedOptionList {
+      public pbc::IPopsicleList<global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption> UninterpretedOptionList {
         get { return result.uninterpretedOption_; }
       }
       public int UninterpretedOptionCount {
@@ -5577,7 +5577,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
       }
       
       
-      public scg::IList<global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption> UninterpretedOptionList {
+      public pbc::IPopsicleList<global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption> UninterpretedOptionList {
         get { return result.uninterpretedOption_; }
       }
       public int UninterpretedOptionCount {
@@ -5824,7 +5824,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
       }
       
       
-      public scg::IList<global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption> UninterpretedOptionList {
+      public pbc::IPopsicleList<global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption> UninterpretedOptionList {
         get { return result.uninterpretedOption_; }
       }
       public int UninterpretedOptionCount {
@@ -6071,7 +6071,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
       }
       
       
-      public scg::IList<global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption> UninterpretedOptionList {
+      public pbc::IPopsicleList<global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption> UninterpretedOptionList {
         get { return result.uninterpretedOption_; }
       }
       public int UninterpretedOptionCount {
@@ -6692,7 +6692,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
       }
       
       
-      public scg::IList<global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption.Types.NamePart> NameList {
+      public pbc::IPopsicleList<global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption.Types.NamePart> NameList {
         get { return result.name_; }
       }
       public int NameCount {

src/ProtocolBuffers/ProtocolBuffers.csproj

@@ -42,6 +42,7 @@
     <Compile Include="AbstractMessage.cs" />
     <Compile Include="ByteString.cs" />
     <Compile Include="Collections\Enumerables.cs" />
+    <Compile Include="Collections\IPopsicleList.cs" />
     <Compile Include="Collections\PopsicleList.cs" />
     <Compile Include="Delegates.cs" />
     <Compile Include="CodedInputStream.cs" />

todo.txt

@@ -11,6 +11,5 @@ Current task list (not in order)
 - Add RegisterAllExtensions
 - Add ToBuilder changes from Google's r92 (done? Need to check)
 - Silverlight changes (as per email to Jon)
-- Extension registration/initialization code?
 - Bring service generation into line with Java
 - Build protoc as a dll and use directly from protogen