Working on a pipeline pattern

Author: Craig W. Selbert

ConsoleApplication/Program.cs

@@ -1,11 +1,10 @@
 using System;
-using System.Diagnostics.Eventing.Reader;
 using Ninject;
 using UMV.Reference.ClassLibrary.Interfaces;
 using UMV.Reference.ClassLibrary.Ninject;
 using UMV.Reference.Patterns;
+using UMV.Reference.Patterns.Aspects;
 using UMV.Reference.Patterns.Models;
-using UMV.Reference.Patterns.Operations;
 
 namespace UMV.Reference.ConsoleApplication
 {
@@ -20,30 +19,21 @@ static void Main(string[] args)
             Console.ReadLine();
         }
 
-
-
         private static void PipelineExample()
         {
             var context = new Member();
 
-            context = new Pipeline<Member>()
-            .Register(new TimeToExecuteOperation<Member>())
-            .Register(new TimeToExecuteOperation<Member>())
-            .Register(new TimeToExecuteOperation<Member>())
-            .Execute(context);
-        }
+            // Build up your pipeline
+            var pipeline = new Pipeline<Member>()
+                .Register(member => { member.FirstName = "Craig"; throw new Exception("Test"); return member; });
 
-        private static void PipelineBuilderExample()
-        {
-            var context = new Member();
+            // Add aspects around the pipline 
+            var exceptionLogginAspect = new ExceptionLoggingAspect<Member>(pipeline.Execute);
 
-            var pipeline = new PipelineBuilder<Member>()
-            .Register(new TimeToExecuteOperation<Member>())
-            .Register(new TimeToExecuteOperation<Member>())
-            .Register(new TimeToExecuteOperation<Member>())
-            .Build();
+            // Execute 
+            context = exceptionLogginAspect.Execute(context);
 
-            context = pipeline.Execute(context);
+            Console.WriteLine(context.FirstName);
         }
 
         private static void IoCExample()

Patterns/Pipeline/Aspects/ExceptionLoggingAspect.cs

@@ -0,0 +1,28 @@
+using System;
+
+namespace UMV.Reference.Patterns.Aspects
+{
+    public class ExceptionLoggingAspect<T>
+    {
+        public ExceptionLoggingAspect(Func<T, T> action)
+        {
+            Handle = action;
+        }
+
+        public T Execute(T input)
+        {
+            try
+            {
+                return Handle(input);
+            }
+            catch (Exception ex)
+            {
+                Console.WriteLine(ex.ToString());
+                return (T)Activator.CreateInstance(typeof(T));
+            }
+        }
+
+        private Func<T, T> Handle { get; set; }
+
+    }
+}

Patterns/Pipeline/Operations/IOperation.cs

@@ -1,29 +1,26 @@
+using System;
+using System.Collections.Generic;
 using System.Threading.Tasks;
-using UMV.Reference.Patterns.Operations;
 
 namespace UMV.Reference.Patterns
 {
     public class Pipeline<T>
     {
-        private IOperation<T> _root;
+        private readonly List<Func<T,T>> _operations = new List<Func<T,T>>();
 
-        public Pipeline<T> Register(IOperation<T> operation)
+        public Pipeline<T> Register(Func<T,T> operation)
         {
-            if (_root == null)
-            {
-                _root = operation;
-            }
-            else
-            {
-                _root.Register(operation);
-            }
-
+            _operations.Add(operation);
             return this;
         }
 
         public T Execute(T context)
         {
-            return _root.Execute(context);
+            foreach (var operation in _operations)
+            {
+                context = operation.Invoke(context);
+            }
+            return context;
         }
     }
-}
+}

Patterns/Pipeline/Operations/Operation.cs

@@ -44,10 +44,7 @@
     <Compile Include="Pipeline\Models\Address.cs" />
     <Compile Include="Pipeline\Models\Member.cs" />
     <Compile Include="Pipeline\Models\Message.cs" />
-    <Compile Include="Pipeline\Operations\TimeToExecuteOperation.cs" />
-    <Compile Include="Pipeline\Operations\Operation.cs" />
-    <Compile Include="Pipeline\Operations\IOperation.cs" />
-    <Compile Include="Pipeline\PipelineBuilder.cs" />
+    <Compile Include="Pipeline\Aspects\ExceptionLoggingAspect.cs" />
     <Compile Include="Pipeline\Pipeline.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
   </ItemGroup>