IDisposable GC.SuppressFinalize(this) location

I use a default IDisposable implementation template (pattern) for my code.

snippet:

public void Dispose()
{
    Dispose(true);

    GC.SuppressFinalize(this);
}

protected virtual void Dispose(bool isDisposing)
{
    if (!this.disposed)
    {
        if (isDisposing)
        {
            //cleanup managed resources
        }

        //cleanup unmanaged resources

        this.disposed = true;
    }
}

My question: why is the call "GC.SuppressFinalize(this)" in the Dispose public method? I would place "GC.SuppressFinalize(this)" in the "if (isDisposing)" section of the protected method, after disposing managed resources.

Like this:

protected virtual void Dispose(bool isDisposing)
{
    if (!this.disposed)
    {
       if (isDisposing)
       {
           //cleanup managed resources

           GC.SuppressFinalize(this);
       }

       //cleanup unmanaged resources

       this.disposed = true;
    }
}

c# .net idisposable suppressfinalize

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1 Answer

I suppose its a clear case of Template Design pattern.

Your abstract class is Designed to take care of all important/necessary tasks required (Here, GC.SuppressFinalize(this)), and allowing a derived class to override only some part of the code.

There are 2 cases here:
Snippet 1, SuppressFinalize, in Dispose
Snippet 2, SuppressFinalize, in Dispose(true)

Here, Snippet 1, makes sure that GC.SuppressFinalize is always executed. While snippet 2, leaves the execution of GC.SuppressFinalize at the mercy of derived class.

So, by putting GC.SuppressFinalize, in Dispose method, you as a designer of your class will always make sure that irrespective of whatever code written by derived classes, GC.SuppressFinalize will be executed.

This is only the benefit of writing SuppressFinalize in Dispose rather then Dispose(true).

answered 2009-03-03T08:55:30.847

IDisposable GC.SuppressFinalize(this) location

1 Answer

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