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Neuron
Neuron

Reputation: 5831

Do I really need to implement Dispose(Boolean)?

I am working on a bunch of classes in some pretty old code. Many implement the IDisposable interface and the Dispose() method. But from what I have read, any class implementing IDisposable should always also implement Dispose(Boolean).

Even the code generated by Visual Basic to help implement IDisposable suggest this (sorry about the VB..):

#Region "IDisposable Support"
    Private mDisposed As Boolean

    ' IDisposable
    Protected Overridable Sub Dispose(disposing As Boolean)
        If Not mDisposed Then
            If disposing Then
                ' TODO: dispose managed state (managed objects).
            End If

            ' TODO: free unmanaged resources (unmanaged objects) and override Finalize() below.
            ' TODO: set large fields to null.
        End If
        mDisposed = True
    End Sub

    ' TODO: override Finalize() only if Dispose(disposing As Boolean) above has code to free unmanaged resources.
    'Protected Overrides Sub Finalize()
    '    ' Do not change this code.  Put cleanup code in Dispose(disposing As Boolean) above.
    '    Dispose(False)
    '    MyBase.Finalize()
    'End Sub

    ' This code added by Visual Basic to correctly implement the disposable pattern.
    Public Sub Dispose() Implements IDisposable.Dispose
        ' Do not change this code.  Put cleanup code in Dispose(disposing As Boolean) above.
        Dispose(True)
        ' TODO: uncomment the following line if Finalize() is overridden above.
        ' GC.SuppressFinalize(Me)
    End Sub
#End Region

It comes with a Dispose(Boolean) and a Dispose() method, while the Finalize() method is commented, suggesting it is the only thing that is optional.

What I find confusing however is, if I don't implement the Finalize() method, the Dispose(Boolean) method seemingly becomes obsolete, as it will literally always be called with disposing == true. From my understanding this would result in the exact same execution logic, apart from the method added on top of the stack.

Am I missing something or can I safely ditch Dispose(Boolean)?

Upvotes: 0

Views: 270

Answers (1)

Davesoft
Davesoft

Reputation: 764

In most cases you can indeed skip the parameter, since you don't have any 'real' disposing to do. Though, imagine that your class was 'Domain Controller + Active Directory + Webserver + Scheduler' all wrapped into a single horrid god-class. You're class might get the woodpecker treatment of being told to dispose over and over again, without the parameter, you don't have any way of tracking 'Im already disposing and can ignore this extra dispose request'

Hans Passant's comment sums the situation quite nicely. A lot of what you are seeing is legacy and may not be needed anymore, but '20mins ago' it was necessary and automation is a blessing.

Upvotes: 2

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