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Tester-Doer Pattern In .Net

In this article, we will discuss tester-doer pattern in .net. The purpose of this pattern is to avoid performance issues that occur due to a potential exception throwing code.

Potential Exception Throwing Code

Consider the following code.

List<string> values = someClass.GetAllValues();
Console.WriteLine(values.Count);

The preceding code is potential exception throwing code, because the code will throw an exception if the variable ‘values’ is null. Due to the exception, the code performance degrades.

The performance of potential exception throwing code could be improved using tester-doer pattern.

Tester-Doer Pattern

In this design pattern, potential exception throwing code is broken into 2 parts

Tester – The code test the condition
Doer – The code performs a potentially exception throwing operation.

So the preceding code is replaced with

List < string > values = someClass.GetAllValues();
if (values != null) // Tester
{
	Console.WriteLine(values.Count); // Doer
}

The preceding code is an example of the tester-doer pattern.

Posted By -	Karan Gupta

Posted On -	Wednesday, October 14, 2015

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