Re: Safe handles and Marshal class

Two things:

1. You do not need to declare handle, SafeHandle class has protected member handle.
2. You are exposing handle publicly which is not good.


-----Original Message-----
From: Discussion of development on the .NET platform using any managed language [mailto:[email protected]] On Behalf Of Peter Ritchie
Sent: Tuesday, February 12, 2008 15:11
To: [email protected]
Subject: Re: [DOTNET-CLR] Safe handles and Marshal class

For some reason I was thinking native memory with Marshal and
Marshal.AllocCoTaskMem--which has no "handle"...

I haven't seen anything like that for native global heap handles; but, off
the top of my head, this might be useful:
 /// <summary>
 /// Class to encapsulate a native global memory handle
 /// </summary>
 /// <revisionHistory><revision name="Peter Ritchie" date="12-feb-
08">Created.</revision></revisionHistory>
 public class SafeGlobalMemoryHandle : SafeHandle
 {
  private IntPtr handle;

  public SafeGlobalMemoryHandle(int size)
  {
   handle = Marshal.AllocHGlobal();
  }

  #region SafeHandle overrides
  protected override bool ReleaseHandle()
  {
   IntPtr toFree =
System.Threading.Interlocked.Exchange(ref handle, IntPtr.Zero);
   Marshal.FreeHGlobal(toFree);
  }

  public override bool IsInvalid
  {
   get { return handle != IntPtr.Zero; }
  }
  #endregion SafeHandle overrides

  /// <summary>
  /// implicit operator so a SafeGloblaMemoryHandle may be
uses in place of an IntPtr
  /// </summary>
  /// <param
name="safeGlobalMemoryHandle">SafeGlobalMemoryHandle in question</param>
  /// <returns>IntPtr representing the native global memory
handle</returns>
  /// <remarks>Use with caution, not all IntPtr's are global
memory handles.</remarks>
  public static implicit operator IntPtr
(SafeGlobalMemoryHandle safeGlobalMemoryHandle)
  {
   return safeGlobalMemoryHandle.handle;
  }
 }

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