Disposable C# Snippets

Visual Studio code snippets were brought up a couple times today.  Which reminded me of the only two snippets I’ve ever written and used.  I think they’re useful to save me some typing.  In C# whenever you have some class that is holding onto unmanaged resources, or even a lot of managed resources, you really need to make it IDisposable.  The problem is it’s a fair amount of repetitive typing to get there. 

I have two versions: one for a base class and one for a derived class.  You use the Base Dispose Pattern snippet if your class is the first class in your hierarchy that implements IDisposable.  You use the Derived Dispose Pattern snippet if your class is derived from another class that implements IDisposable.  Just put your caret on a line within class scope, but outside method scope.  Hit the old “Ctrl K X”, select “My Code Snippets” from the context menu, then find the correct Dispose Pattern.  Don’t forget to add IDisposable to your class definition if it’s a base disposable class.

After the snippet is pasted you’ll have a couple sections to fill in.  The fill in sections are marked with comments.  The managed section is where you clean up your managed member data.  You would do this by calling Dispose() on IDisposable types and breaking references by setting them to null.  This makes it easier for the garbage collector to know what to clean up.  For example:

// if x is a disposable type:

if (x != null)

{

    x.Dispose();

    x = null;

}

 

// if x is not a disposable reference type:

x = null;

The unmanaged section is where you would clean up any native resources used by your class.  For example: you would close any open win32 handles there.

The disposed member variable can be used in debugging to find out if your object is being referenced after it’s been disposed.  This is a bad thing, but you can quickly check for it by using code like the following:

public void MyMethod()

{

    if (disposed)

    {

        throw new ObjectDisposedException(“MyClass.MyMethod() called on disposed object!”);

    }

    // TODO: write method code.

}

Copy these two files into your DocumentsVisual Studio 2008Code SnippetsVisual C#My Code Snippets folder:

Base Dispose Pattern.snippet:

<?xml version=“1.0“ encoding=“utf-8“?>

<CodeSnippets xmlns=“http://schemas.microsoft.com/VisualStudio/2005/CodeSnippet“>

  <CodeSnippet Format=“1.0.0“>

    <Header>

      <Title>

        Base Dispose Pattern

      </Title>

    </Header>

    <Snippet>

      <Declarations>

        <Literal Editable=“false“>

          <ID>classname</ID>

          <ToolTip>The name of this class.</ToolTip>

          <Default>BaseResource</Default>

          <Function>ClassName()</Function>

        </Literal>

      </Declarations>

      <Code Language=“CSharp“>

        <![CDATA[private bool disposed = false;

 

        public void Dispose()

        {

            Dispose(true);

            GC.SuppressFinalize(this);

        }

 

        protected virtual void Dispose(bool disposing)

        {

            if (!disposed)

            {

                if (disposing) // Managed:

                {

                }

                // Unmanaged:

            }

            disposed = true;

        }

 

        ~$classname$()

        {

            Dispose(false);

        }]]>

      </Code>

    </Snippet>

  </CodeSnippet>

</CodeSnippets>

Derived Dispose Pattern.snippet:

<?xml version=“1.0“ encoding=“utf-8“?>

<CodeSnippets xmlns=“http://schemas.microsoft.com/VisualStudio/2005/CodeSnippet“>

  <CodeSnippet Format=“1.0.0“>

    <Header>

      <Title>

        Derived Dispose Pattern

      </Title>

    </Header>

    <Snippet>

      <Code Language=“CSharp“>

        <![CDATA[private bool disposed = false;

 

        protected override void Dispose(bool disposing)

        {

            if (!disposed)

            {

                try

                {

                    if (disposing) // Managed:

                    {

                    }

                    // Unmanaged:

                    disposed = true;

                }

                finally

                {

                    base.Dispose(disposing);

                }

            }

        }]]>

      </Code>

    </Snippet>

  </CodeSnippet>

</CodeSnippets>

Enjoy!