For example:
using (disposable object here)
{
}
What determines if I can use an object in this way?
Would this work correctly?
using (WebClient webClient = new WebClient())
{
}
4 Answers
In order to be used in a using statement, a class needs to implement the IDisposable interface.
In your example, WebClient derives from Component, which implements IDisposable, so it would indeed work.
4 Comments
Ani
+1. An implicit conversion to
IDisposable is also acceptable, as is an implicit dynamic conversion.
Kit
Not that it's useful, but using (null) {} works. I haven't bothered to find out why yet and not sure how I got into this bit of triviality.
Frédéric Hamidi
@Kit, it works because the C# spec says:
If a null resource is acquired, then no call to Dispose is made, and no exception is thrown.Kit
Oh yeah. I forgot that. I guess my example is the canonical case to illustrate that!
You can use it if the class implements the IDisposable interface. This keyword is basically just syntactic sugar for calling the object's IDisposable.Dispose() method automatically after the using block.
The Dispose() method:
Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
Comments
The object provided in the using statement must implement the IDisposable interface.
This interface provides the Dispose method, which should release the object's resources.
Reference: http://msdn.microsoft.com/en-us/library/yh598w02(v=vs.80).aspx
answered Dec 17, 2010 at 13:32
Jón Trausti Arason
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