slashdotdash · paulroho · May 22, 2015 · May 22, 2015 · May 22, 2015
diff --git a/src/PersistenceExample/App.config b/src/PersistenceExample/App.config
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<configuration>
+    <startup> 
+
+    <supportedRuntime version="v2.0.50727"/></startup>
+</configuration>
diff --git a/src/PersistenceExample/PersistenceExample.csproj b/src/PersistenceExample/PersistenceExample.csproj
@@ -0,0 +1,64 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="12.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
+  <PropertyGroup>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
+    <ProjectGuid>{3C45B29F-222C-4914-A4F8-3775438A4070}</ProjectGuid>
+    <OutputType>Exe</OutputType>
+    <AppDesignerFolder>Properties</AppDesignerFolder>
+    <RootNamespace>PersistenceExample</RootNamespace>
+    <AssemblyName>PersistenceExample</AssemblyName>
+    <TargetFrameworkVersion>v3.5</TargetFrameworkVersion>
+    <FileAlignment>512</FileAlignment>
+    <TargetFrameworkProfile />
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
+    <PlatformTarget>AnyCPU</PlatformTarget>
+    <DebugSymbols>true</DebugSymbols>
+    <DebugType>full</DebugType>
+    <Optimize>false</Optimize>
+    <OutputPath>bin\Debug\</OutputPath>
+    <DefineConstants>DEBUG;TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
+    <PlatformTarget>AnyCPU</PlatformTarget>
+    <DebugType>pdbonly</DebugType>
+    <Optimize>true</Optimize>
+    <OutputPath>bin\Release\</OutputPath>
+    <DefineConstants>TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+  </PropertyGroup>
+  <ItemGroup>
+    <Reference Include="System" />
+    <Reference Include="System.Core" />
+    <Reference Include="System.Xml.Linq" />
+    <Reference Include="System.Data.DataSetExtensions" />
+    <Reference Include="System.Data" />
+    <Reference Include="System.Xml" />
+  </ItemGroup>
+  <ItemGroup>
+    <Compile Include="Program.cs" />
+    <Compile Include="Properties\AssemblyInfo.cs" />
+  </ItemGroup>
+  <ItemGroup>
+    <None Include="App.config" />
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\Stateless\Stateless.csproj">
+      <Project>{a15eec02-60ec-4705-a58b-a6ecd55a9628}</Project>
+      <Name>Stateless</Name>
+    </ProjectReference>
+  </ItemGroup>
+  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
+  <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
+       Other similar extension points exist, see Microsoft.Common.targets.
+  <Target Name="BeforeBuild">
+  </Target>
+  <Target Name="AfterBuild">
+  </Target>
+  -->
+</Project>
diff --git a/src/PersistenceExample/Program.cs b/src/PersistenceExample/Program.cs
@@ -0,0 +1,51 @@
+using System;
+using Stateless;
+
+namespace PersistenceExample
+{
+    static class Program
+    {
+        static void Main()
+        {
+            try
+            {
+                const string on = "On";
+                const string off = "Off";
+                const char space = ' ';
+
+                Console.WriteLine("Press <space> to toggle the switch. Any other key will raise an error.");
+
+                var savedState = off;
+                Func<string> loadMethod = () =>
+                {
+                    Console.WriteLine("(Persistence: state {0} has been loaded)", savedState);
+                    return savedState;
+                };
+                Action<string> saveMethod = state =>
+                {
+                    savedState = state; 
+                    Console.WriteLine("(Persistence: state {0} has been saved)", state);
+                };
+
+                var initialState = loadMethod();
+                var onOffSwitch = new StateMachine<string, char>(initialState, saveMethod);
+
+                onOffSwitch.Configure(off).Permit(space, on);
+                onOffSwitch.Configure(on).Permit(space, off);
+
+                while (true)
+                {
+                    Console.WriteLine("Switch is in state: " + onOffSwitch.State);
+                    var pressed = Console.ReadKey(true).KeyChar;
+                    onOffSwitch.Fire(pressed);
+                }
+            }
+            catch (Exception ex)
+            {
+                Console.WriteLine("Exception: " + ex.Message);
+                Console.WriteLine("Press any key to continue...");
+                Console.ReadKey(true);
+            }
+        }
+    }
+}
diff --git a/src/PersistenceExample/Properties/AssemblyInfo.cs b/src/PersistenceExample/Properties/AssemblyInfo.cs
@@ -0,0 +1,36 @@
+using System.Reflection;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+
+// General Information about an assembly is controlled through the following 
+// set of attributes. Change these attribute values to modify the information
+// associated with an assembly.
+[assembly: AssemblyTitle("PersistenceExample")]
+[assembly: AssemblyDescription("")]
+[assembly: AssemblyConfiguration("")]
+[assembly: AssemblyCompany("")]
+[assembly: AssemblyProduct("PersistenceExample")]
+[assembly: AssemblyCopyright("Copyright ©  2015")]
+[assembly: AssemblyTrademark("")]
+[assembly: AssemblyCulture("")]
+
+// Setting ComVisible to false makes the types in this assembly not visible 
+// to COM components.  If you need to access a type in this assembly from 
+// COM, set the ComVisible attribute to true on that type.
+[assembly: ComVisible(false)]
+
+// The following GUID is for the ID of the typelib if this project is exposed to COM
+[assembly: Guid("2a02c2e2-2c9a-433f-8e35-1e1e72e3625c")]
+
+// Version information for an assembly consists of the following four values:
+//
+//      Major Version
+//      Minor Version 
+//      Build Number
+//      Revision
+//
+// You can specify all the values or you can default the Build and Revision Numbers 
+// by using the '*' as shown below:
+// [assembly: AssemblyVersion("1.0.*")]
+[assembly: AssemblyVersion("1.0.0.0")]
+[assembly: AssemblyFileVersion("1.0.0.0")]
diff --git a/src/Stateless.Tests/StateMachineFixture.cs b/src/Stateless.Tests/StateMachineFixture.cs
@@ -66,6 +66,31 @@ public void StateCanBeStoredExternally()
             Assert.AreEqual(State.C, state);
         }
 
+        [Test]
+        public void StateIsWrittenJustOnceOnEveryStateTransition()
+        {
+            var state = State.B;
+            var saveCount = 0;
+            Action<State> stateMutator = s =>
+            {
+                saveCount++;
+                state = s;
+            };
+            var sm = new StateMachine<State, Trigger>(State.B, stateMutator);
+            sm.Configure(State.B).Permit(Trigger.X, State.C);
+            sm.Configure(State.C).Permit(Trigger.Y, State.B);
+            Assert.AreEqual(State.B, sm.State);
+            Assert.AreEqual(State.B, state);
+            sm.Fire(Trigger.X);
+            Assert.AreEqual(State.C, sm.State);
+            Assert.AreEqual(State.C, state);
+            Assert.AreEqual(1, saveCount);
+            sm.Fire(Trigger.Y);
+            Assert.AreEqual(State.B, sm.State);
+            Assert.AreEqual(State.B, state);
+            Assert.AreEqual(2, saveCount);
+        }
+
         [Test]
         public void SubstateIsIncludedInCurrentState()
         {

diff --git a/src/Stateless.sln b/src/Stateless.sln
@@ -1,6 +1,8 @@
 
-Microsoft Visual Studio Solution File, Format Version 11.00
-# Visual Studio 2010
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio 2013
+VisualStudioVersion = 12.0.31101.0
+MinimumVisualStudioVersion = 10.0.40219.1
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Stateless", "Stateless\Stateless.csproj", "{A15EEC02-60EC-4705-A58B-A6ECD55A9628}"
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Stateless.Tests", "Stateless.Tests\Stateless.Tests.csproj", "{70AD8860-1F5E-4F78-9276-CAD498EDDF73}"
@@ -11,6 +13,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "TelephoneCallExample", "Tel
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "BugTrackerExample", "BugTrackerExample\BugTrackerExample.csproj", "{3A56311E-C3AC-4E34-A1DF-CA5042A31039}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "PersistenceExample", "PersistenceExample\PersistenceExample.csproj", "{3C45B29F-222C-4914-A4F8-3775438A4070}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -37,6 +41,10 @@ Global
 		{3A56311E-C3AC-4E34-A1DF-CA5042A31039}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{3A56311E-C3AC-4E34-A1DF-CA5042A31039}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{3A56311E-C3AC-4E34-A1DF-CA5042A31039}.Release|Any CPU.Build.0 = Release|Any CPU
+		{3C45B29F-222C-4914-A4F8-3775438A4070}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{3C45B29F-222C-4914-A4F8-3775438A4070}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{3C45B29F-222C-4914-A4F8-3775438A4070}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{3C45B29F-222C-4914-A4F8-3775438A4070}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE

diff --git a/src/Stateless/StateMachine.cs b/src/Stateless/StateMachine.cs
@@ -39,6 +39,22 @@ public StateMachine(TState initialState)
             _stateMutator = s => reference.State = s;
         }
 
+        /// <summary>
+        /// Construct a state machine with external storage (saving only).
+        /// </summary>
+        /// <param name="initialState">The initial state.</param>
+        /// <param name="stateMutator">An action that will be called to write new state values.</param>
+        public StateMachine(TState initialState, Action<TState> stateMutator)
+        {
+            var reference = new StateReference { State = initialState };
+            _stateAccessor = () => reference.State;
+            _stateMutator = s =>
+            {
+                reference.State = s;
+                stateMutator(s);
+            };
+        }
+
         /// <summary>
         /// The current state.
         /// </summary>