Singleton : Singleton Pattern « Design Patterns « C# / C Sharp

1. C# / C Sharp
2. Design Patterns
3. Singleton Pattern

Singleton

        

using System;
using System.Reflection;


namespace tera.commons.utils
{
    public static class Singleton<T> where T : class
    {
        /// <summary>
        /// The singleton instance itself
        /// </summary>
        private static volatile T m_Instance;
        /// <summary>
        /// The object used to lock the entire singleton repository.
        /// </summary>
        private static object m_Lock = new object();

        /// <summary>
        /// Get the singleton instance of type <see cref="T"/>.
        /// </summary>
        public static T Instance
        {
            get
            {
                // Only create a new instance if there is no instance yet
                // Lock the entire singleton repository and check again for any racing conditions
                if (m_Instance == null)
                    lock (m_Lock)
                        if (m_Instance == null)
                        {
                            // Try to get the private/protected constructor from type T
                            ConstructorInfo constructorInfo;
                            try { constructorInfo = typeof(T).GetConstructor(BindingFlags.Instance | BindingFlags.NonPublic, null, new Type[0], null); }
                            //  Could not get the  private/protected constructor
                            catch (Exception exception) { throw new Exception("DefaultMessage", exception); }

                            // Make sure we have a private/protected constructor and not an internal one
                            if (constructorInfo == null || constructorInfo.IsAssembly)
                                throw new Exception("DefaultMessage");

                            // Create a new instance by invoking the constructor
                            m_Instance = (T)constructorInfo.Invoke(null);
                        }

                // The earlier created instance
                return m_Instance;
            }
        }
    }
}

   
    
    
    
    
    
    
    
  

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