IsNothing versus Is Nothing

vb.net nothing
Luke Girvin picture Luke Girvin · Aug 8, 2008 · Viewed 198k times · Source

Does anyone here use VB.NET and have a strong preference for or against using IsNothing as opposed to Is Nothing (for example, If IsNothing(anObject) or If anObject Is Nothing...)? If so, why?

EDIT: If you think they're both equally acceptable, do you think it's best to pick one and stick with it, or is it OK to mix them?

Answer

lomaxx picture lomaxx · Aug 8, 2008

If you take a look at the MSIL as it's being executed you'll see that it doesn't compile down to the exact same code. When you use IsNothing() it actually makes a call to that method as opposed to just evaluating the expression.

The reason I would tend to lean towards using "Is Nothing" is when I'm negating it becomes "IsNot Nothing' rather than "Not IsNothing(object)" which I personally feel looks more readable.

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