IDisposable Interface
Definition
Important
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Provides a mechanism for releasing unmanaged resources.
public interface class IDisposablepublic interface IDisposable[System.Runtime.InteropServices.ComVisible(true)]
public interface IDisposabletype IDisposable = interface[<System.Runtime.InteropServices.ComVisible(true)>]
type IDisposable = interfacePublic Interface IDisposable- Derived
- Attributes
Examples
The following example demonstrates how to create a resource class that implements the IDisposable interface.
#using <System.dll>
#using <System.Windows.Forms.dll>
using namespace System;
using namespace System::ComponentModel;
using namespace System::Windows::Forms;
// The following example demonstrates how to create a class that
// implements the IDisposable interface and the IDisposable.Dispose
// method with finalization to clean up unmanaged resources.
//
public ref class MyResource: public IDisposable
{
private:
// Pointer to an external unmanaged resource.
IntPtr handle;
// A managed resource this class uses.
Component^ component;
// Track whether Dispose has been called.
bool disposed;
public:
// The class constructor.
MyResource( IntPtr handle, Component^ component )
{
this->handle = handle;
this->component = component;
disposed = false;
}
// This method is called if the user explicitly disposes of the
// object (by calling the Dispose method in other managed languages,
// or the destructor in C++). The compiler emits as a call to
// GC::SuppressFinalize( this ) for you, so there is no need to
// call it here.
~MyResource()
{
// Dispose of managed resources.
component->~Component();
// Call C++ finalizer to clean up unmanaged resources.
this->!MyResource();
// Mark the class as disposed. This flag allows you to throw an
// exception if a disposed object is accessed.
disposed = true;
}
// Use interop to call the method necessary to clean up the
// unmanaged resource.
//
[System::Runtime::InteropServices::DllImport("Kernel32")]
static Boolean CloseHandle( IntPtr handle );
// The C++ finalizer destructor ensures that unmanaged resources get
// released if the user releases the object without explicitly
// disposing of it.
//
!MyResource()
{
// Call the appropriate methods to clean up unmanaged
// resources here. If disposing is false when Dispose(bool,
// disposing) is called, only the following code is executed.
CloseHandle( handle );
handle = IntPtr::Zero;
}
};
void main()
{
// Insert code here to create and use the MyResource object.
MyResource^ mr = gcnew MyResource((IntPtr) 42, (Component^) gcnew Button());
mr->~MyResource();
}
using System;
using System.ComponentModel;
// The following example demonstrates how to create
// a resource class that implements the IDisposable interface
// and the IDisposable.Dispose method.
public class DisposeExample
{
// A base class that implements IDisposable.
// By implementing IDisposable, you are announcing that
// instances of this type allocate scarce resources.
public class MyResource: IDisposable
{
// Pointer to an external unmanaged resource.
private IntPtr handle;
// Other managed resource this class uses.
private Component component = new Component();
// Track whether Dispose has been called.
private bool disposed = false;
// The class constructor.
public MyResource(IntPtr handle)
{
this.handle = handle;
}
// Implement IDisposable.
// Do not make this method virtual.
// A derived class should not be able to override this method.
public void Dispose()
{
Dispose(disposing: true);
// This object will be cleaned up by the Dispose method.
// Therefore, you should call GC.SuppressFinalize to
// take this object off the finalization queue
// and prevent finalization code for this object
// from executing a second time.
GC.SuppressFinalize(this);
}
// Dispose(bool disposing) executes in two distinct scenarios.
// If disposing equals true, the method has been called directly
// or indirectly by a user's code. Managed and unmanaged resources
// can be disposed.
// If disposing equals false, the method has been called by the
// runtime from inside the finalizer and you should not reference
// other objects. Only unmanaged resources can be disposed.
protected virtual void Dispose(bool disposing)
{
// Check to see if Dispose has already been called.
if(!this.disposed)
{
// If disposing equals true, dispose all managed
// and unmanaged resources.
if(disposing)
{
// Dispose managed resources.
component.Dispose();
}
// Call the appropriate methods to clean up
// unmanaged resources here.
// If disposing is false,
// only the following code is executed.
CloseHandle(handle);
handle = IntPtr.Zero;
// Note disposing has been done.
disposed = true;
}
}
// Use interop to call the method necessary
// to clean up the unmanaged resource.
[System.Runtime.InteropServices.DllImport("Kernel32")]
private extern static Boolean CloseHandle(IntPtr handle);
// Use C# finalizer syntax for finalization code.
// This finalizer will run only if the Dispose method
// does not get called.
// It gives your base class the opportunity to finalize.
// Do not provide finalizer in types derived from this class.
~MyResource()
{
// Do not re-create Dispose clean-up code here.
// Calling Dispose(disposing: false) is optimal in terms of
// readability and maintainability.
Dispose(disposing: false);
}
}
public static void Main()
{
// Insert code here to create
// and use the MyResource object.
}
}
// The following example demonstrates how to create
// a resource class that implements the IDisposable interface
// and the IDisposable.Dispose method.
open System
open System.ComponentModel
open System.Runtime.InteropServices
// Use interop to call the method necessary
// to clean up the unmanaged resource.
[<DllImport "Kernel32">]
extern Boolean CloseHandle(nativeint handle)
// A base class that implements IDisposable.
// By implementing IDisposable, you are announcing that
// instances of this type allocate scarce resources.
type MyResource(handle: nativeint) =
// Pointer to an external unmanaged resource.
let mutable handle = handle
// Other managed resource this class uses.
let comp = new Component()
// Track whether Dispose has been called.
let mutable disposed = false
// Implement IDisposable.
// Do not make this method virtual.
// A derived class should not be able to override this method.
interface IDisposable with
member this.Dispose() =
this.Dispose true
// This object will be cleaned up by the Dispose method.
// Therefore, you should call GC.SuppressFinalize to
// take this object off the finalization queue
// and prevent finalization code for this object
// from executing a second time.
GC.SuppressFinalize this
// Dispose(bool disposing) executes in two distinct scenarios.
// If disposing equals true, the method has been called directly
// or indirectly by a user's code. Managed and unmanaged resources
// can be disposed.
// If disposing equals false, the method has been called by the
// runtime from inside the finalizer and you should not reference
// other objects. Only unmanaged resources can be disposed.
abstract Dispose: bool -> unit
override _.Dispose(disposing) =
// Check to see if Dispose has already been called.
if not disposed then
// If disposing equals true, dispose all managed
// and unmanaged resources.
if disposing then
// Dispose managed resources.
comp.Dispose()
// Call the appropriate methods to clean up
// unmanaged resources here.
// If disposing is false,
// only the following code is executed.
CloseHandle handle |> ignore
handle <- IntPtr.Zero
// Note disposing has been done.
disposed <- true
// This finalizer will run only if the Dispose method
// does not get called.
// It gives your base class the opportunity to finalize.
// Do not provide finalizer in types derived from this class.
override this.Finalize() =
// Do not re-create Dispose clean-up code here.
// Calling Dispose(disposing: false) is optimal in terms of
// readability and maintainability.
this.Dispose false
Imports System.ComponentModel
' The following example demonstrates how to create
' a resource class that implements the IDisposable interface
' and the IDisposable.Dispose method.
Public Class DisposeExample
' A class that implements IDisposable.
' By implementing IDisposable, you are announcing that
' instances of this type allocate scarce resources.
Public Class MyResource
Implements IDisposable
' Pointer to an external unmanaged resource.
Private handle As IntPtr
' Other managed resource this class uses.
Private component As component
' Track whether Dispose has been called.
Private disposed As Boolean = False
' The class constructor.
Public Sub New(ByVal handle As IntPtr)
Me.handle = handle
End Sub
' Implement IDisposable.
' Do not make this method virtual.
' A derived class should not be able to override this method.
Public Overloads Sub Dispose() Implements IDisposable.Dispose
Dispose(disposing:=True)
' This object will be cleaned up by the Dispose method.
' Therefore, you should call GC.SupressFinalize to
' take this object off the finalization queue
' and prevent finalization code for this object
' from executing a second time.
GC.SuppressFinalize(Me)
End Sub
' Dispose(bool disposing) executes in two distinct scenarios.
' If disposing equals true, the method has been called directly
' or indirectly by a user's code. Managed and unmanaged resources
' can be disposed.
' If disposing equals false, the method has been called by the
' runtime from inside the finalizer and you should not reference
' other objects. Only unmanaged resources can be disposed.
Protected Overridable Overloads Sub Dispose(ByVal disposing As Boolean)
' Check to see if Dispose has already been called.
If Not Me.disposed Then
' If disposing equals true, dispose all managed
' and unmanaged resources.
If disposing Then
' Dispose managed resources.
component.Dispose()
End If
' Call the appropriate methods to clean up
' unmanaged resources here.
' If disposing is false,
' only the following code is executed.
CloseHandle(handle)
handle = IntPtr.Zero
' Note disposing has been done.
disposed = True
End If
End Sub
' Use interop to call the method necessary
' to clean up the unmanaged resource.
<System.Runtime.InteropServices.DllImport("Kernel32")> _
Private Shared Function CloseHandle(ByVal handle As IntPtr) As [Boolean]
End Function
' This finalizer will run only if the Dispose method
' does not get called.
' It gives your base class the opportunity to finalize.
' Do not provide finalize methods in types derived from this class.
Protected Overrides Sub Finalize()
' Do not re-create Dispose clean-up code here.
' Calling Dispose(disposing:=False) is optimal in terms of
' readability and maintainability.
Dispose(disposing:=False)
MyBase.Finalize()
End Sub
End Class
Public Shared Sub Main()
' Insert code here to create
' and use the MyResource object.
End Sub
End Class
Remarks
For more information about this API, see Supplemental API remarks for IDisposable.
Methods
| Dispose() |
Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources. |
Applies to
See also
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