In daily coding, consider the Tester-Doer pattern for members that may throw exceptions in common scenarios to avoid performance problems related to exceptions.
The Tester-Doer pattern divides a call that might throw exceptions into two parts: a Tester and a Doer. The Tester performs a test for the state that can cause the Doer to throw an exception. The test is inserted just before the code that throws the exception,
thereby guarding against the exception.
The following code example shows a Tester-Doer pattern.
if (uiElement.Exists(true, false)) // Tester
{
uiElement.Click(); // Doer
}In the above example, if we don‘t use a Tester here, when the uiElement does not exist, the Doer will throw an exception and the application running will down. So the Tester-Doer pattern in very
important in daily coding.
C# - Tester-Doer Pattern
原文：http://blog.csdn.net/troubleshooter/article/details/18401491
