Remove "new NotImplementedExceptions" from corefx assemblies.

[ghost]

Sites found by tooling:

• System.Net.HttpListener.DisconnectAsyncResult::AsyncState.get()

• System.Net.HttpListener.DisconnectAsyncResult::AsyncWaitHandle.get()

• System.Net.HttpListener.DisconnectAsyncResult::CompletedSynchronously.get()

• System.Net.HttpListener.DisconnectAsyncResult::IsCompleted.get()

• System.Net.WebSockets.HttpListenerWebSocketContext::CopyPrincipal(IPrincipal)

• System.Net.WebSockets.WebSocketBase.WebSocketOperation::ProcessAction_IndicateReceiveComplete (Nullable<ArraySegment>, BufferType, Action, Buffer[], uint, IntPtr)

• System.Net.Mime.EightBitStream::DecodeBytes(byte[], int, int)

• System.Net.Mime.EightBitStream::EncodeBytes(byte[], int, int)

• System.Net.Mime.EightBitStream::GetEncodedString()

• System.Net.Mime.MimeBasePart::BeginSend(BaseWriter, AsyncCallback, bool, object)

• System.Net.Mime.MimeBasePart::Send(BaseWriter, bool)

• System.Runtime.Serialization.Json.ReflectionJsonReader::ReadSimpleDictionary(XmlReaderDelegator, XmlObjectSerializerReadContext, CollectionDataContract, Type, object)

• System.Runtime.Serialization.NullPrimitiveDataContract::ReadMethodName.get()

• System.Runtime.Serialization.NullPrimitiveDataContract::ReadXmlValue(XmlReaderDelegator, XmlObjectSerializerReadContext)

• System.Runtime.Serialization.NullPrimitiveDataContract::WriteMethodName.get()

• System.Runtime.Serialization.NullPrimitiveDataContract::WriteXmlElement(XmlWriterDelegator, object, XmlObjectSerializerWriteContext, XmlDictionaryString, XmlDictionaryString)

• System.Runtime.Serialization.NullPrimitiveDataContract::WriteXmlValue(XmlWriterDelegator, object, XmlObjectSerializerWriteContext)

• System.Runtime.Serialization.XmlDataContract::ReflectionCreateXmlSerializable(Type)

• System.Runtime.Serialization.XmlObjectSerializerReadContext::IsBitSet(byte[], int)

• System.ServiceModel.Channels.StreamConnection::GetCoreTransport()

• System.ServiceModel.Dispatcher.DispatchRuntime.UnhandledActionInvoker::InvokeBegin(object, object[], AsyncCallback, object)

• System.ServiceModel.Dispatcher.DispatchRuntime.UnhandledActionInvoker::InvokeEnd(object, object[], IAsyncResult)

• MS.Internal.Xml.Cache.XPathDocumentBuilder::WriteEntityRef(string)

• System.Xml.Serialization.ReflectionXmlSerializationReader::WriteArray(ArrayMapping, bool, bool, string, int, Fixup, Member)

• System.Xml.Serialization.ReflectionXmlSerializationReader::WriteAttribute(Member, object)

• System.Xml.Serialization.ReflectionXmlSerializationReader::WriteElement(ElementAccessor, bool, bool, bool, string, int, int, Fixup, Member)

• System.Xml.Serialization.ReflectionXmlSerializationReader::WriteLiteralStructMethod(StructMapping, bool, bool, string)

• System.Xml.Serialization.XmlSerializer::CreateReader()

• System.Xml.Serialization.XmlSerializer::CreateWriter()

• System.Xml.Serialization.XmlSerializer::Deserialize(XmlSerializationReader)

• System.Xml.Serialization.XmlSerializer::Serialize(object, XmlSerializationWriter)

• System.Xml.XmlRawWriter::WriteEndElementAsync(string, string, string)

• System.Xml.XmlRawWriter::WriteNamespaceDeclarationAsync(string, string)

• System.Xml.XmlReader::GetValueAsync()

• System.Xml.XmlReader::ReadAsync()

• System.Xml.XmlResolver::GetEntityAsync(Uri, string, Type)

• System.Xml.XmlTextWriterBase64Encoder::WriteCharsAsync(char[], int, int)

• System.Xml.XmlWellFormedWriter.NamespaceResolverProxy::System.Xml.IXmlNamespaceResolver.GetNamespacesInScope(XmlNamespaceScope)

• System.Xml.XmlWriter::FlushAsync()

• System.Xml.XmlWriter::WriteBase64Async(byte[], int, int)

• System.Xml.XmlWriter::WriteCDataAsync(string)

• System.Xml.XmlWriter::WriteCharEntityAsync(char)

• System.Xml.XmlWriter::WriteCharsAsync(char[], int, int)

• System.Xml.XmlWriter::WriteCommentAsync(string)

• System.Xml.XmlWriter::WriteDocTypeAsync(string, string, string, string)

• System.Xml.XmlWriter::WriteEndAttributeAsync()

• System.Xml.XmlWriter::WriteEndDocumentAsync()

• System.Xml.XmlWriter::WriteEndElementAsync()

• System.Xml.XmlWriter::WriteEntityRefAsync(string)

• System.Xml.XmlWriter::WriteFullEndElementAsync()

• System.Xml.XmlWriter::WriteProcessingInstructionAsync(string, string)

• System.Xml.XmlWriter::WriteRawAsync(char[], int, int)

• System.Xml.XmlWriter::WriteRawAsync(string)

• System.Xml.XmlWriter::WriteStartAttributeAsync(string, string, string)

• System.Xml.XmlWriter::WriteStartDocumentAsync()

• System.Xml.XmlWriter::WriteStartDocumentAsync(bool)

• System.Xml.XmlWriter::WriteStartElementAsync(string, string, string)

• System.Xml.XmlWriter::WriteStringAsync(string)

• System.Xml.XmlWriter::WriteSurrogateCharEntityAsync(char, char)

• System.Xml.XmlWriter::WriteWhitespaceAsync(string)

• System.Xml.Xsl.XsltOld.ContainerAction::Compile(Compiler)

• System.Runtime.InteropServices.WindowsRuntime.WindowsRuntimeBuffer::EnsureHasMarshalProxy()

• System.Security.Cryptography.DSA::DerivedClassMustOverride()

• System.Security.Cryptography.ECDiffieHellmanPublicKey::ToXmlString()

• System.Security.Cryptography.ECDsa::FromXmlString(string)

• System.Security.Cryptography.ECDsa::ToXmlString(bool)

• System.Security.Cryptography.RandomNumberGenerator::GetNonZeroBytes(byte[])

• System.Security.Cryptography.RSA::DerivedClassMustOverride()

• System.Security.Cryptography.AsymmetricAlgorithm::FromXmlString(string)

• System.Security.Cryptography.AsymmetricAlgorithm::KeyExchangeAlgorithm.get()

• System.Security.Cryptography.AsymmetricAlgorithm::SignatureAlgorithm.get()

• System.Security.Cryptography.AsymmetricAlgorithm::ToXmlString(bool)

• System.Transactions.InternalEnlistment::PromotableSinglePhaseNotification.get()

• System.Transactions.InternalEnlistment::ResourceManagerIdentifier.get()

How to remove:

1. Include the following in your .csproj file:

    <Compile Include="$(CommonPath)\System\NotImplemented.cs">
      <Link>Common\System\NotImplemented.cs</Link>
    </Compile>

Options for removing “throw new NotImplementedException()”:

If you can implement the missing functionality now:

Do so.

If this is functionality that’s not supported on a particular framework or OS, replace with

throw new PlatformNotSupportedException(SR.xxx);

If this is an api that needs to throw NotImplemented for backward compat reasons, replace with:

throw NotImplemented.ByDesign;

or

throw NotImplemented.ByDesignWithMessage(SR.xxx);

If this is a virtual api method that’s only intended to work when overridden by another class, replace with:

throw new NotSupportedException(SR.xxx);

(Unless required for backward compat, refrain from throwing NotImplemented out of these.)

If this is a virtual non-api method that’s only intended to work when overridden by another class, replace with:

An abstract method.

If this is a compiler or toolchain intrinsic that only needs a body to make C# happy:

throw new NotSupportedException();

If this is true undone work and you just can’t fix it now, replace with:

throw NotImplemented.ActiveIssue(“https://github.com/dotnet/corefx/issues/xxx”);

The string will not leak out via Exception.Message. The string is for tooling and human readers only. In the past, we’ve usually added an inline comment but the trouble with those is that IL-based tooling can’t read comments.

[danmoseley]

@davidsh some of these are networking. @atsushikan looks like already filtered out those that are of the form NotImplemented.ByDesignWithMessage.

I made the list into checkboxes but it seems to have iffy formatting.

[danmoseley]

@atsushikan I do'nt think there is anything particular to UWP here. Although we should do this pass, I'm going to move out of that milestone as I don't think it's required to ship it. Tests should catch anything UWP specific. Let me know if I'm wrong.

[hrrrrustic]

@danmoseley Is this issue still relevant? (4 years after👀). I found about 200 throw new NotImplementedException() at the latest commit in main

If this is a virtual non-api method that’s only intended to work when overridden by another class, replace with:
An abstract method.

I found some cases where whole class is not abstract (for example MimeBasePart or InternalEnlistment), should it go through api design review to get abstract?

[danmoseley]

Hmm. Many do seem to be cases where NotSupportedException should properly be thrown (cases where an interface is incompletely implemented, or a member is expected to be overridden by a derived class).

I am not sure whether that is worth changing (which would be a breaking change, albeit a relatively low risk one presumably).

I think the original goal of the opener here was to make it possible to grep for NotImplementedException and reliably know that they all represent incomplete work that deserves our attention.

@jkotas how do you feel about this goal?

[jkotas]

I do not have a strong opinion about this.

Here are some statistics about patterns used under src/libraries:

• throw new NotImplemetedException: 1197 instances
• NotImplemented.ByDesign: 203 instances
• throw new NotSupportedException: 1567 instances

So we are close to break-even between NotImplemetedException and NotSupportedException.

throw new NotImplementedException() is frequently used to mean: This is not implemented, I do not expect this method to be ever called, but it can be implemented if needed. I think it is very reasonable to use it with this meaning. For example, the recently added Json source generator added number of instances like that in https://github.com/dotnet/runtime/blob/main/src/libraries/System.Text.Json/gen/Reflection/TypeWrapper.cs. I expect that vast majority of NotImplementedException uses in this repo fall into this category.

[danmoseley]

My feeling is that it is not worth making a push here and we should encourage contributors to look at other issues.

[joperezr]

I agree with both comments above, so closing this issue for now. Feel free to re-open if you think this is an issue that should be addressed.