sealed classes

Author: theodorzoulias

README.md

@@ -2,6 +2,8 @@
 
 # Simple TPL Dataflow Pipelines
 
+[![Nuget](https://img.shields.io/nuget/v/SimpleTplDataflowPipelines)](https://www.nuget.org/packages/SimpleTplDataflowPipelines/)
+
 This library helps at building simple [TPL Dataflow](https://docs.microsoft.com/en-us/dotnet/standard/parallel-programming/dataflow-task-parallel-library) pipelines,
 that enforce the following guarantees:
 
@@ -100,15 +102,15 @@ the `Completion` property of the individual blocks. Observing this exception jus
 this block was not the first that failed. It is possible that the `PipelineException`
 may coexist with other exceptions in the same dataflow block.
 
-## Discussion
+## Comparison with Encapsulate
 
 It might be helpful to compare the functionality offered by this library with the
 functionality offered by the [`DataflowBlock.Encapsulate`](https://docs.microsoft.com/en-us/dotnet/api/system.threading.tasks.dataflow.dataflowblock.encapsulate) method.
 The result of this method is similar with the result of the `ToPipeline` method: both return
 an [`IPropagatorBlock<TInput, TOutput>`](https://docs.microsoft.com/en-us/dotnet/api/system.threading.tasks.dataflow.ipropagatorblock-2) implementation
 (a block that is both a target and a source). The `DataflowBlock.Encapsulate`
 accepts a `target` and a `source` block, and returns a propagator that delegates to
-these two blocks. The two blocks are not linked automatically in any way, and the completion
+these two blocks. The two blocks are **not** linked automatically in any way, and the completion
 of the propagator represents the completion of the second (the `source`) block only.
 On the contrary the `ToPipeline` returns a propagator that links all the dataflow
 blocks tightly in both directions, and its `Completion` represents the completion of all its
@@ -129,7 +131,6 @@ bool received = receivable.TryReceive(out string item);
 ## Embedding the library into your project
 
 You can install the [SimpleTplDataflowPipelines](https://www.nuget.org/packages/SimpleTplDataflowPipelines/) NuGet package.
-[![Nuget](https://img.shields.io/nuget/v/SimpleTplDataflowPipelines)](https://www.nuget.org/packages/SimpleTplDataflowPipelines/)
 You can also [download](https://github.com/theodorzoulias/SimpleTplDataflowPipelines/releases) the project and build it locally, or just
 embed the single code file [`PipelineBuilder.cs`](https://github.com/theodorzoulias/SimpleTplDataflowPipelines/blob/main/src/SimpleTplDataflowPipelines/PipelineBuilder.cs)
 (~400 lines of code) into your project.

src/SimpleTplDataflowPipelines/PipelineBuilder.cs

@@ -40,8 +40,9 @@ internal delegate Action LinkDelegate(
     /// <summary>
     /// Represents an error that occurred in an other dataflow block, owned by the same pipeline.
     /// </summary>
-    public class PipelineException : Exception
+    public sealed class PipelineException : Exception
     {
+        // Prevent this type from being publicly creatable.
         internal PipelineException() : base("An other dataflow block, owned by the same pipeline, failed.") { }
     }
 
@@ -201,9 +202,15 @@ internal static Task CreatePipeline<TInput>(ITargetBlock<TInput> target,
             return Task.WhenAll(completions).ContinueWith(t =>
             {
                 if (!t.IsFaulted) return t;
+
+                // Propagate all non-PipelineException errors.
+                // At least one should exist, unless reflection was used.
+                var filtered = t.Exception.InnerExceptions
+                    .Where(ex => !(ex is PipelineException));
+                if (!filtered.Any()) throw new InvalidOperationException(
+                    "After filtering out the PipelineExceptions, no other exception was left.");
                 var tcs = new TaskCompletionSource<object>();
-                tcs.SetException(
-                    t.Exception.InnerExceptions.Where(ex => !(ex is PipelineException)));
+                tcs.SetException(filtered);
                 return tcs.Task;
             }, default(CancellationToken), TaskContinuationOptions.DenyChildAttach, TaskScheduler.Default).Unwrap();
         }
@@ -301,7 +308,7 @@ internal static T[] Append<T>(T[] array, T item)
         }
     }
 
-    internal class Pipeline<TInput> : ITargetBlock<TInput>
+    internal sealed class Pipeline<TInput> : ITargetBlock<TInput>
     {
         private readonly ITargetBlock<TInput> _target;
         private readonly Task _completion;
@@ -323,7 +330,7 @@ public DataflowMessageStatus OfferMessage(DataflowMessageHeader messageHeader,
                 => _target.OfferMessage(messageHeader, messageValue, source, consumeToAccept);
     }
 
-    internal class Pipeline<TInput, TOutput> : IPropagatorBlock<TInput, TOutput>,
+    internal sealed class Pipeline<TInput, TOutput> : IPropagatorBlock<TInput, TOutput>,
         IReceivableSourceBlock<TOutput>
     {
         private readonly ITargetBlock<TInput> _target;

src/SimpleTplDataflowPipelines/SimpleTplDataflowPipelines.csproj

@@ -4,7 +4,7 @@
     <TargetFrameworks>netstandard2.0;net46</TargetFrameworks>
     <Authors>Theodor Zoulias</Authors>
     <Description>A library that helps at building simple TPL Dataflow pipelines</Description>
-    <Version>1.0.7</Version>
+    <Version>1.1.0</Version>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <PackageLicenseFile>LICENSE</PackageLicenseFile>
     <PackageIcon>logo_32.png</PackageIcon>