July 2006
Intermediate to advanced
768 pages
16h 43m
English
Content preview from Agile Principles, Patterns, and Practices in C#
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25. Null Object
© Jennifer M. Kohnke
Faultily faultless, icily regular, splendidly null, Dead perfection, no more.
—Lord Alfred Tennyson (1809–1892)
Description
Consider the following code:
Employee e = DB.GetEmployee("Bob");if (e != null && e.IsTimeToPay(today)) e.Pay();
We ask the database for an Employee object named "Bob". The DB object will return null if no such object exists. Otherwise, it will return the requested instance of Employee. If the employee exists and is owed payment we invoke the pay method.
We’ve all written code like this before. The idiom is common because, in C-based languages, the first expression of the && is evaluated ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
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