Dispose Pattern in C#

Agenda

Destructor and Finalizer in C#
IDisposable and RAII
Dispose Pattern for Managed and

Destructor and Finalizer in C#

Destructor in C#

Destructor in C# language created with tilde (“~”) is

Finalizer Problem

Time of finalizer call is not defined in .NET, that

IDisposable and RAII

Interface IDisposable

Provides a mechanism for releasing unmanaged resources.

RAII Idiom

RAII – Resource Acquisition Is Initialization
RAII means that resource should

Keyword using

Keyword “using” not completely implements RAII

// Opening file inside using

Method Dispose

Dispose method differs from destructor in that way that it

Dispose Pattern for Managed and Unmanaged Resources

Dispose Pattern

Taking into account all previously mentioned, we have to implement

Managed and Unmanaged Resources

Unmanaged resources – IntPtr, socket descriptors, any OS

Sample Resource Wrapper

class NativeResourceWrapper : IDisposable {   // IntPtr – unmanaged resource descriptor   private

Main Idea of Dispose Pattern

The main idea of Dispose Pattern is:

1. Interface Implementation

Class that has both managed and unmanaged resources implements

2. Method Dispose(bool disposing)

Class contains method Dispose(bool disposing) that does all

3. Method Dispose()

Dispose method implementation: first we call Dispose(true), then we

Notes to GC.SupressFinalize() Call

GC.SuppressFinalize() should be called after Dispose(true) but not

4. Parameter “disposing”

Method Dispose(bool disposing) has two parts:
If this method called from Dispose (disposing parameter

5. Finalizer

[OPTIONAL] Class may have finalizer and call Dispose(bool disposing) from it

6. Field “disposed”

The good practice is to create special Boolean field

Objects with Critical Finalization

7. Object with Critical Finalization

Class may be inherited from CriticalFinalizerObject:
Finalizer for

Simplified Dispose Pattern

Simplifying Dispose Pattern

Most difficulties with Dispose pattern implementation based on assumption

Simplified Dispose Pattern

Used only for managed resources

class SomethingWithManagedResources : IDisposable {   public void

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