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How to know when a Class/Object is Disposed/Finalized/ = NothingHi,
I have made some classes, but when they are Finalized/Disposed or simply "MyClass = Nothing", I want to trigger this action, and ask to save unsaved changes. How should I do this? I'm kind of testing with a Base-Class from which all my classes inherit to override the Finalize-method, but it doesn't really work... :-( Any help our hints would be really appreciated! Thanks a lot in advance, Pieter Hi,
Try having your class implement Idisposable that will add a dispose method where you can clean things up. I dont think setting the class to nothing will trigger dispose. Try using the myclass.dispose instead of myclass=nothing Public Class test Implements IDisposable Public Sub Dispose() Implements System.IDisposable.Dispose MessageBox.Show("Disposing") End Sub End Class Ken ----------------------- Show quote "DraguVaso" <pietercou***@hotmail.com> wrote in message news:%23vn5PiK0FHA.1028@TK2MSFTNGP12.phx.gbl... > Hi, > > I have made some classes, but when they are Finalized/Disposed or simply > "MyClass = Nothing", I want to trigger this action, and ask to save > unsaved changes. > > How should I do this? I'm kind of testing with a Base-Class from which all > my classes inherit to override the Finalize-method, but it doesn't really > work... :-( > > Any help our hints would be really appreciated! > > Thanks a lot in advance, > > Pieter > > > Hi Pieter,
Check out the following SDK reference on the IDisposable Interface. It includes (int the Remarks section) good advice and an excellent sample of the way you ought to implement the Dispose method while avoiding the types of problems you're describing. http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfsystemidisposableclasstopic.asp -- Show quoteHTH, Kevin Spencer Microsoft MVP ..Net Developer Ambiguity has a certain quality to it. "DraguVaso" <pietercou***@hotmail.com> wrote in message news:%23vn5PiK0FHA.1028@TK2MSFTNGP12.phx.gbl... > Hi, > > I have made some classes, but when they are Finalized/Disposed or simply > "MyClass = Nothing", I want to trigger this action, and ask to save > unsaved changes. > > How should I do this? I'm kind of testing with a Base-Class from which all > my classes inherit to override the Finalize-method, but it doesn't really > work... :-( > > Any help our hints would be really appreciated! > > Thanks a lot in advance, > > Pieter > > > "DraguVaso" <pietercou***@hotmail.com> wrote in message Finalizing/Disposing are definitely not the same as setting anews:%23vn5PiK0FHA.1028@TK2MSFTNGP12.phx.gbl... > I have made some classes, but when they are Finalized/Disposed > or simply "MyClass = Nothing", I want to trigger this action, and > ask to save unsaved changes. Variable to Nothing. If you have code that you want to be called when the object is "no longer needed", have the class implement IDisposable and put the code into your Dispose method (have a look at the Dispose code written into any Windows Forms you create). It is /convention/ that when discarding an object that /has/ a Dispose method, the caller /should/ do so (sadly, this isn't actually /enforced/ anywhere). Also, with regards this bit ... "ask to save unsaved changes" .... spare a thought for /how/ you intend to do this. The quick answer is to pop up a MessageBox - but this could leave you a bit stuck further down the line if you want to, say, reuse these classes in a Windows Service; these don't like MessageBox's very much at all. HTH, Phill W. DraguVaso wrote:
<snip> > I have made some classes, but when they are Finalized/Disposed or simply <snip>> "MyClass = Nothing", I want to trigger this action, and ask to save unsaved > changes. > > How should I do this? I'm kind of testing with a Base-Class from which all > my classes inherit to override the Finalize-method, but it doesn't really > work... :-( Alas, you're asking for deterministic finalization, and this is not provided in .Net. The closest to this is an Open/Close pattern: you implement these methods and the clients (users of your class) must call them at the appropriate times. This way you may have some tracking logic inside your class (reference counting, for exemple), that would detect the last 'Close' and take action if the data wasn't saved (raise an event, for example). Hope this helps... Regards, Branco. ok, thanks a lot for the help guys!
Pieter <branco.medei***@gmail.com> wrote in message Show quote news:1129322404.851853.54470@g44g2000cwa.googlegroups.com... > > DraguVaso wrote: > <snip> >> I have made some classes, but when they are Finalized/Disposed or simply >> "MyClass = Nothing", I want to trigger this action, and ask to save >> unsaved >> changes. >> >> How should I do this? I'm kind of testing with a Base-Class from which >> all >> my classes inherit to override the Finalize-method, but it doesn't really >> work... :-( > <snip> > > Alas, you're asking for deterministic finalization, and this is not > provided in .Net. The closest to this is an Open/Close pattern: you > implement these methods and the clients (users of your class) must call > them at the appropriate times. > > This way you may have some tracking logic inside your class (reference > counting, for exemple), that would detect the last 'Close' and take > action if the data wasn't saved (raise an event, for example). > > Hope this helps... > > Regards, > > Branco. >  |
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