public virtual string GetErrorMessage(
	CommandLineParser parser
)Public Overridable Function GetErrorMessage ( 
	parser As CommandLineParser
) As String
Dim instance As ClassValidationAttribute
Dim parser As CommandLineParser
Dim returnValue As String
returnValue = instance.GetErrorMessage(parser)public:
virtual String^ GetErrorMessage(
	CommandLineParser^ parser
)Override this method in a derived class to provide a custom error message. Otherwise, it will return a generic error message.