Was this page helpful?
Your feedback about this content is important. Let us know what you think.
Additional feedback?
1500 characters remaining
Export (0) Print
Expand All
Expand Minimize
Important This document may not represent best practices for current development, links to downloads and other resources may no longer be valid. Current recommended version can be found here.

Disposable types should declare finalizer

TypeName

DisposableTypesShouldDeclareFinalizer

CheckId

CA2216

Category

Microsoft.Usage

Breaking Change

Non Breaking

A type that implements System.IDisposable, and has fields that suggest the use of unmanaged resources, does not implement a finalizer as described by Object.Finalize.

A violation of this rule is reported if the disposable type contains fields of the following types:

To fix a violation of this rule, implement a finalizer that calls your Dispose method.

It is safe to suppress a warning from this rule if the type does not implement IDisposable for the purpose of releasing unmanaged resources.

The following example shows a type that violates this rule.

using System;  
using System.Runtime.InteropServices;

namespace UsageLibrary
{
    public class  DisposeMissingFinalize :IDisposable
    {
        private bool disposed = false;
        private IntPtr unmanagedResource;

        [DllImport("native.dll")]
        private static extern IntPtr AllocateUnmanagedResource();

        [DllImport("native.dll")]
        private static extern void FreeUnmanagedResource(IntPtr p);

        DisposeMissingFinalize()
        {
            unmanagedResource = AllocateUnmanagedResource();
        }

        protected virtual void Dispose(bool disposing) 
        {
            if (!disposed) 
            {
                // Dispose of resources held by this instance.
                FreeUnmanagedResource(unmanagedResource);
                disposed = true;

                // Suppress finalization of this disposed instance. 
                if (disposing)
                {
                    GC.SuppressFinalize(this);
                }
            }
        }

        public void Dispose()
        {
            Dispose(true);
        }

        // Disposable types with unmanaged resources implement a finalizer. 
        // Uncomment the following code to satisfy rule: 
        //  DisposableTypesShouldDeclareFinalizer 
        // ~TypeA() 
        // { 
        //     Dispose(false); 
        // }
    }
}

Community Additions

ADD
Show:
© 2015 Microsoft