Null object pattern

2. Check if it’s Null all the time

3. http://www.erlang.se/doc/programming_rules.shtml#HDR11

9. Employee
null
getEmployeeByDB()
Employee
NullableEmployee
getEmployeeByDB()
Null Object Pattern
ANullableEmployee

10. Abstract Class
private NullClass inherit
static readonly NullClass
•Return the NullClass
as usual

21. Null Object Pattern change the culture
which check if it’s valid all the time.
If this object should be fail, it do nothing or
return the failure status.