using uCalcSoftware; var uc = new uCalc(); // In C# and VB you should use "using". // In C++ you can flag a uCalc object for // auto-release with Owned(), or by setting // the last parameter of the constructor to true. uc.IsDefault = true; // Set uc as the default uCalc object uCalc.DefaultInstance.DefineVariable("Value = 'Original uc object'"); Console.WriteLine(uCalc.DefaultInstance.EvalStr("Value")); // Outputs: Original uc object // Use "using" so that the object is auto-released when it it goes out of scope using (var uCalcTemp = new uCalc()) { uCalcTemp.IsDefault = true; // Set uCalcTemp as the default uCalc object uCalc.DefaultInstance.DefineVariable("Value = 'uCalcTemp object'"); Console.WriteLine(uCalc.DefaultInstance.EvalStr("Value")); // uCalcTemp object } // uCalcTemp goes out of scope here, and the default uCalc object reverts back to uc Console.WriteLine(uCalc.DefaultInstance.EvalStr("Value")); // Original uc object { /*using*/ var uCalcSticky = new uCalc(); // remains the default even after going out of scope uCalcSticky.IsDefault = true; // Set uCalcSticky as the default uCalc object uCalc.DefaultInstance.DefineVariable("Value = 'uCalcSticky object'"); Console.WriteLine(uCalc.DefaultInstance.EvalStr("Value")); // Outputs: uCalcSticky object } // The uCalcSticky object itself goes out of scope here, but internally it remains the default uCalc object Console.WriteLine(uCalc.DefaultInstance.EvalStr("Value"));