C# 4 and .NET 4

esource Management ❘ OC181
}
' Visual Basic
Using r As New Resource
r.Foo()
End Using
// F# use binding
let rs =
use r = new Resource()
r.Foo()
// r.Dispose called implicitly
// F# using expression
let bar (r : Resource) =
r.Foo()
using (new Resource()) bar
override finalize
If a class contains native resources that must be freed, the class must override the Finalize() method from
the Object class. With C#, this is done by writing a destructor. C++/CLI has a special syntax with the !
prefi x to defi ne a fi nalizer. Within a fi nalizer, you cannot dispose contained objects that have a fi nalizer
as well because the order of fi nalization is not guaranteed. That ’ s why the Dispose pattern defi nes an
additional Dispose() method with a Boolean parameter. With C++/CLI, it is not necessary to implement
this pattern in the code because this is done by the compiler. The C++/CLI destructor implements both
Dispose() methods. With Visual Basic, both Dispose() and the fi nalizer must be implemented manually.
However, most Visual Basic classes do not use native resources directly, just with the help of other classes.
With Visual Basic, usually it is not necessary to override the Finalize() method, but an implementation of
the Dispose() method is often required.
Writing a destructor with C# overrides the Finalize() method of the base class. A
C++/CLI destructor implements the IDisposable interface.
// C#
public class Resource: IDisposable
{
~Resource // override Finalize
{
Dispose(false);
}
protected virtual void Dispose(bool disposing)
{
if (disposing) // dispose embedded members
{
}
// release resources of this class
GC.SuppressFinalize(this);
}
public void Dispose()
{
Dispose(true);
}
}
code snippet CSharp/Resource.cs
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