How to: Perform Lazy Initialization of Objects
.NET Framework 4.5
The System.Lazy<T> class simplifies the work of performing lazy initialization and instantiation of objects. By initializing objects in a lazy manner, you can avoid having to create them at all if they are never needed, or you can postpone their initialization until they are first accessed. For more information, see Lazy Initialization.
The following example shows how to initialize a value with Lazy<T>. Assume that the lazy variable might not be needed, depending on some other code that sets the someCondition variable to true or false.
static bool someCondition = false; //Initializing a value with a big computation, computed in parallel Lazy<int> _data = new Lazy<int>(delegate { return ParallelEnumerable.Range(0, 1000). Select(i => Compute(i)).Aggregate((x,y) => x + y); }, LazyExecutionMode.EnsureSingleThreadSafeExecution); // Do some work that may or may not set someCondition to true. // ... // Initialize the data only if necessary if (someCondition) { if (_data.Value > 100) { Console.WriteLine("Good data"); } }
The following example shows how to use the System.Threading.ThreadLocal<T> class to initialize a type that is visible only to the current object instance on the current thread.
