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