#681 – Avoid Using the new Keyword To Hide Methods

You can use the new keyword in a derived class to hide a method in a base class, rather than overriding it.  In other words, the method in the derived class is not polymorphic, so if the method is called from a variable whose type matches the base class, the method in the base class will be called, rather than the method in the subclass.

// In Dog - public virtual void Bark()
// In Terrier : Dog - public new void Bark()

Dog d = new Terrier("Bob");
d.Bark();   // Dog.Bark called, rather than Terrier.Bark

If a Terrier really is-a type of Dog, then this lack of polymorphism on the Bark method doesn’t really make sense.  If you wanted to add a method to Terrier that was really something entirely new, you should give it a new name to avoid confusion, rather than using the new keyword.

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About Sean
Software developer in the Twin Cities area, passionate about .NET technologies. Equally passionate about my own personal projects related to family history and preservation of family stories and photos.

2 Responses to #681 – Avoid Using the new Keyword To Hide Methods

  1. Pingback: #682 – The Real Reason for the new Keyword « 2,000 Things You Should Know About C#

  2. Pingback: All Things of World

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