int Add(int x, int y) {     return (2 + 1) + (1); }

/// <summary> /// LazyExpression /// </summary> /// <typeparam name="T">T</typeparam> public class LazyExpression<T> {     Func<T> thunk;     public LazyExpression(Func<T> Thunk)     {         thunk = Thunk;     }     public T Evaluate()     {         return thunk();     } } /// <summary> /// LazyBoolExpression /// </summary> public static class LazyBoolExpression {     public static bool And(LazyExpression<bool> LHS, LazyExpression<bool> RHS)     {         return LHS.Evaluate() && RHS.Evaluate();     }     public static bool Or(LazyExpression<bool> LHS, LazyExpression<bool> RHS)     {         return LHS.Evaluate() == true ? true : RHS.Evaluate();     } } /// <summary> /// LazyMemoizedExpression /// </summary> /// <typeparam name="T"></typeparam> public class LazyMemoizedExpression<T> {     bool thunked;     T value;     Func<T> thunk;     public LazyMemoizedExpression(Func<T> Thunk)     {         thunked = false;         thunk = Thunk;     }     public T Evaluate()     {         if (!thunked)         {             value = thunk();             thunked = true;         }         return value;     } }

///<summary> ///Laziestheexpressiontest. ///</summary> [TestCase] publicvoidLazyExpressionTest() { varlme1=newLazyExpression<int>(()=>2+1); varlme2=newLazyExpression<int>(()=>1); Assert.AreEqual(4,Add(lme1,lme2)); } ///<summary> ///Addsthespecifiedx. ///</summary> ///<paramname="x">Thex.</param> ///<paramname="y">They.</param> ///<returns>result</returns> privateintAdd(LazyExpression<int>x,LazyExpression<int>y) { returnx.Evaluate()+y.Evaluate(); } ///<summary> ///Laziestheexpressionwithlogic. ///</summary> [TestCase] publicvoidLazyExpressionWithLogic() { varexp1=newLazyExpression<bool>(()=>true); varexp2=newLazyExpression<bool>(()=>true||false); if(LazyBoolExpression.And(exp1,exp2)) { Console.WriteLine("lazyand"); } if(LazyBoolExpression.Or(exp1,exp2)) { Console.WriteLine("lazyor"); } } ///<summary> ///Laziesthememoizedexpressiontest. ///</summary> [TestCase] publicvoidLazyMemoizedExpressionTest() { varlme1=newLazyMemoizedExpression<int>(()=>GetIntResult()); Assert.AreEqual(943,lme1.Evaluate()); Assert.AreEqual(943,lme1.Evaluate()); //output: //1passed,0failed,0skipped,took2.80seconds(NUnit2.5). } ///<summary> ///Comparestolazyexpressiontest. ///</summary> [TestCase] publicvoidCompareToLazyExpressionTest() { varlme1=newLazyExpression<int>(()=>GetIntResult()); Assert.AreEqual(943,lme1.Evaluate()); Assert.AreEqual(943,lme1.Evaluate()); //output: //1passed,0failed,0skipped,took4.80seconds(NUnit2.5). } ///<summary> ///Getstheintresult. ///</summary> ///<returns></returns> privateintGetIntResult() { //currentthreadsleeptwosecond. System.Threading.Thread.Sleep(2000); return943; }