Added Week 7 Project

158.326 Software Architecture.sln

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+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 16
+VisualStudioVersion = 16.0.31515.178
+MinimumVisualStudioVersion = 10.0.40219.1
+Global
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {A613E761-D85D-4A76-8EFC-5A095B348A49}
+	EndGlobalSection
+EndGlobal

158326 Week 7 Singletons/158326 Week 7 Singletons.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net5.0</TargetFramework>
+    <RootNamespace>_158326_Week_7_Singletons</RootNamespace>
+  </PropertyGroup>
+
+</Project>

158326 Week 7 Singletons/158326 Week 7 Singletons.sln

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+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 16
+VisualStudioVersion = 16.0.31515.178
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "158326 Week 7 Singletons", "158326 Week 7 Singletons.csproj", "{0540B959-6D66-4CBD-A18F-74344B782EF8}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{0540B959-6D66-4CBD-A18F-74344B782EF8}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{0540B959-6D66-4CBD-A18F-74344B782EF8}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{0540B959-6D66-4CBD-A18F-74344B782EF8}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{0540B959-6D66-4CBD-A18F-74344B782EF8}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {2ED746F5-A191-4E18-B64C-A78216BC01E7}
+	EndGlobalSection
+EndGlobal

158326 Week 7 Singletons/Program.cs

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+using System;
+using System.IO;
+
+namespace _158326_Week_7_Singletons
+{
+    class Program
+    {
+        static void Main(string[] args)
+        {
+            Console.WriteLine("158.326 Software Architecture");
+            Console.WriteLine("\tWeek 7 - Singleton Design Pattern");
+            Console.WriteLine("\tSingletons are instanced classes that can have only 0 or 1 instances of that class in existance in the application (Multitons are a variant that restricts the maximum number of instances)");
+        }
+    }
+
+    /// <summary>
+    /// Represents a singleton file stream; useful for logs etc., where access to a specific file should be performed singularly
+    /// (don't open multiple streams on the same file)
+    /// </summary>
+    sealed class FileSingleton
+    {
+        /// <summary>
+        /// Store the instance in a private, static variable
+        /// </summary>
+        private static FileSingleton instance;
+
+        /// <summary>
+        /// Path of the file to open
+        /// </summary>
+        public static Uri FilePath { get; set; } = new Uri("\\log.txt", UriKind.Relative); // Opens exactly one file stream on log.txt and will always return that stream
+
+        // We can define instance variables here:
+        public FileStream OpenedFileStream { get; set; } // Calling FileSingleton.GetInstance().OpenedFileStream will always return this object
+
+
+        // We can also define  
+
+        /// <summary>
+        /// The default constructor must be implemented, and as private so only functions in this class may call it
+        /// This restricts the creation of this instance to local methods, so by restricting constructor calls
+        /// to GetInstance(), we can ensure that only one instance is created
+        /// </summary>
+        private FileSingleton() { }
+
+        
+        /// <summary>
+        /// Gets the initialised instance of FileSingleton
+        /// </summary>
+        /// <returns></returns>
+        public static FileSingleton GetInstance()
+        {
+            if (instance is null)
+            {
+                instance = new FileSingleton();
+            }
+            return instance;
+        }
+    }
+}