Hi,

I see in many MS example code that looks like this

Public Sub Foo()
dim myCustomer as New Customer
...
myCustomer.Dispose()
myCustomer = Nothing
End Sub

I'm wondering if setting myCustomer = Nothing is necessary in this case?
Since myCustomer is a private variable, once it goes out of scope at the next
line, the reference to the object should be released.

Thanks.

Hao

Hao Jiang wrote:
> Hi,
>
> I see in many MS example code that looks like this
>
> Public Sub Foo()
> dim myCustomer as New Customer
> ...
> myCustomer.Dispose()
> myCustomer = Nothing
> End Sub
>
> I'm wondering if setting myCustomer = Nothing is necessary in this case?
> Since myCustomer is a private variable, once it goes out of scope at the next
> line, the reference to the object should be released.
>
> Thanks.
>
> Hao

That is correct. Removing the reference is pointless in this case.

--
Göran Andersson
_____
http://www.guffa.com

"Hao Jiang" <Hao (E-Mail Removed)> schrieb:
> Public Sub Foo()
> dim myCustomer as New Customer
> ...
> myCustomer.Dispose()
> myCustomer = Nothing
> End Sub
>
> I'm wondering if setting myCustomer = Nothing is necessary in this case?

No, it actually isn't necessary for the reason you mentioned.

--
M S Herfried K. Wagner
M V P <URL:http://dotnet.mvps.org/>
V B <URL:http://dotnet.mvps.org/dotnet/faqs/>

Hao Jiang,
As Göran & Herfried suggests setting myCustomer = Nothing is not needed for
the reason you give.

Instead of calling Dispose outright I would recommend using the new Using
statement in .NET 2.0 (VS 2005). The Using statement ensures that Dispose is
called even if one of the statements contained by the Using throws an
exception.

> Public Sub Foo()
Using myCustomer as New Customer
> ...
End Using
> End Sub

Which is basically the following in .NET 1.x:

Dim myCustomer As New Customer
Try
DoSomething()
Finally
If myCustomer IsNot Nothing Then
myCustomer.Dispose()
End If
End Try

--
Hope this helps
Jay B. Harlow [MVP - Outlook]
..NET Application Architect, Enthusiast, & Evangelist
T.S. Bradley - http://www.tsbradley.net


"Hao Jiang" <Hao (E-Mail Removed)> wrote in message
news:4551F173-DAB8-4F74-AE61-(E-Mail Removed)...
> Hi,
>
> I see in many MS example code that looks like this
>
> Public Sub Foo()
> dim myCustomer as New Customer
> ...
> myCustomer.Dispose()
> myCustomer = Nothing
> End Sub
>
> I'm wondering if setting myCustomer = Nothing is necessary in this case?
> Since myCustomer is a private variable, once it goes out of scope at the
> next
> line, the reference to the object should be released.
>
> Thanks.
>
> Hao

Hao Jiang,

Do you mean with MS samples, samples made by Micrsoft, if so can you than
show us some of those?
(URL's)

Because it is not correct, it is as
dim a as integer = 1 + 1
if a <> 2 then messagebox.show "there was a calculation error"

Thanks in advance,

Cor

"Jay B. Harlow [MVP - Outlook]" <(E-Mail Removed)> schreef in
bericht news:(E-Mail Removed)...
> Hao Jiang,
> As Göran & Herfried suggests setting myCustomer = Nothing is not needed
> for the reason you give.
>
> Instead of calling Dispose outright I would recommend using the new Using
> statement in .NET 2.0 (VS 2005). The Using statement ensures that Dispose
> is called even if one of the statements contained by the Using throws an
> exception.
>
>> Public Sub Foo()
> Using myCustomer as New Customer
>> ...
> End Using
>> End Sub
>
> Which is basically the following in .NET 1.x:
>
> Dim myCustomer As New Customer
> Try
> DoSomething()
> Finally
> If myCustomer IsNot Nothing Then
> myCustomer.Dispose()
> End If
> End Try
>
> --
> Hope this helps
> Jay B. Harlow [MVP - Outlook]
> .NET Application Architect, Enthusiast, & Evangelist
> T.S. Bradley - http://www.tsbradley.net
>
>
> "Hao Jiang" <Hao (E-Mail Removed)> wrote in message
> news:4551F173-DAB8-4F74-AE61-(E-Mail Removed)...
>> Hi,
>>
>> I see in many MS example code that looks like this
>>
>> Public Sub Foo()
>> dim myCustomer as New Customer
>> ...
>> myCustomer.Dispose()
>> myCustomer = Nothing
>> End Sub
>>
>> I'm wondering if setting myCustomer = Nothing is necessary in this case?
>> Since myCustomer is a private variable, once it goes out of scope at the
>> next
>> line, the reference to the object should be released.
>>
>> Thanks.
>>
>> Hao
>

yeah; in vb6 when a variable went out of scope; it automagically
cleaned up after itself


except for DAO-- (which MS just ressurrected)









On Feb 26, 3:30 pm, Hao Jiang <Hao J...@discussions.microsoft.com>
wrote:
> Hi,
>
> I see in many MS example code that looks like this
>
> Public Sub Foo()
> dim myCustomer as New Customer
> ...
> myCustomer.Dispose()
> myCustomer = Nothing
> End Sub
>
> I'm wondering if setting myCustomer = Nothing is necessary in this case?
> Since myCustomer is a private variable, once it goes out of scope at the next
> line, the reference to the object should be released.
>
> Thanks.
>
> Hao

Thanks Goran, Hefried and Jay! That's what I thought.

Cor, please check out the 2nd and 3rd code section on this MS page:
http://support.microsoft.com/kb/888168

Hao

"Cor Ligthert [MVP]" wrote:

> Hao Jiang,
>
> Do you mean with MS samples, samples made by Micrsoft, if so can you than
> show us some of those?
> (URL's)
>
> Because it is not correct, it is as
> dim a as integer = 1 + 1
> if a <> 2 then messagebox.show "there was a calculation error"
>
> Thanks in advance,
>
> Cor
>
> "Jay B. Harlow [MVP - Outlook]" <(E-Mail Removed)> schreef in
> bericht news:(E-Mail Removed)...
> > Hao Jiang,
> > As Göran & Herfried suggests setting myCustomer = Nothing is not needed
> > for the reason you give.
> >
> > Instead of calling Dispose outright I would recommend using the new Using
> > statement in .NET 2.0 (VS 2005). The Using statement ensures that Dispose
> > is called even if one of the statements contained by the Using throws an
> > exception.
> >
> >> Public Sub Foo()
> > Using myCustomer as New Customer
> >> ...
> > End Using
> >> End Sub
> >
> > Which is basically the following in .NET 1.x:
> >
> > Dim myCustomer As New Customer
> > Try
> > DoSomething()
> > Finally
> > If myCustomer IsNot Nothing Then
> > myCustomer.Dispose()
> > End If
> > End Try
> >
> > --
> > Hope this helps
> > Jay B. Harlow [MVP - Outlook]
> > .NET Application Architect, Enthusiast, & Evangelist
> > T.S. Bradley - http://www.tsbradley.net
> >
> >
> > "Hao Jiang" <Hao (E-Mail Removed)> wrote in message
> > news:4551F173-DAB8-4F74-AE61-(E-Mail Removed)...
> >> Hi,
> >>
> >> I see in many MS example code that looks like this
> >>
> >> Public Sub Foo()
> >> dim myCustomer as New Customer
> >> ...
> >> myCustomer.Dispose()
> >> myCustomer = Nothing
> >> End Sub
> >>
> >> I'm wondering if setting myCustomer = Nothing is necessary in this case?
> >> Since myCustomer is a private variable, once it goes out of scope at the
> >> next
> >> line, the reference to the object should be released.
> >>
> >> Thanks.
> >>
> >> Hao
> >
>
>
>

On Feb 26, 5:30 pm, Hao Jiang <Hao J...@discussions.microsoft.com>
wrote:
> Hi,
>
> I see in many MS example code that looks like this
>
> Public Sub Foo()
> dim myCustomer as New Customer
> ...
> myCustomer.Dispose()
> myCustomer = Nothing
> End Sub
>
> I'm wondering if setting myCustomer = Nothing is necessary in this case?
> Since myCustomer is a private variable, once it goes out of scope at the next
> line, the reference to the object should be released.
>
> Thanks.
>
> Hao

Hao,

To be absolutely precise the object is eligible for garbage collection
even before it goes out of scope as long as it's not used anymore. I
don't know how aggressive the GC rules are specifically, but it is
possible that the GC would consider the line myCustomer = Nothing as
having no side effects on the object and would collect the object even
before the line executed. I suppose it's reasonable to theorize that
the JIT compiler could optimize the line away as well.

Brian

Brian

On Feb 27, 11:25 am, Hao Jiang <HaoJi...@discussions.microsoft.com>
wrote:
> Thanks Goran, Hefried and Jay! That's what I thought.
>
> Cor, please check out the 2nd and 3rd code section on this MS page:http://support.microsoft.com/kb/888168
>
> Hao

Hmm...yeah, those are poorly written examples.

Hao,

Thanks, I have sent it further

Cor

"Hao Jiang" <(E-Mail Removed)> schreef in bericht
news:FAA14219-133E-44F6-A858-(E-Mail Removed)...
> Thanks Goran, Hefried and Jay! That's what I thought.
>
> Cor, please check out the 2nd and 3rd code section on this MS page:
> http://support.microsoft.com/kb/888168
>
> Hao
>
> "Cor Ligthert [MVP]" wrote:
>
>> Hao Jiang,
>>
>> Do you mean with MS samples, samples made by Micrsoft, if so can you than
>> show us some of those?
>> (URL's)
>>
>> Because it is not correct, it is as
>> dim a as integer = 1 + 1
>> if a <> 2 then messagebox.show "there was a calculation error"
>>
>> Thanks in advance,
>>
>> Cor
>>
>> "Jay B. Harlow [MVP - Outlook]" <(E-Mail Removed)> schreef in
>> bericht news:(E-Mail Removed)...
>> > Hao Jiang,
>> > As Göran & Herfried suggests setting myCustomer = Nothing is not needed
>> > for the reason you give.
>> >
>> > Instead of calling Dispose outright I would recommend using the new
>> > Using
>> > statement in .NET 2.0 (VS 2005). The Using statement ensures that
>> > Dispose
>> > is called even if one of the statements contained by the Using throws
>> > an
>> > exception.
>> >
>> >> Public Sub Foo()
>> > Using myCustomer as New Customer
>> >> ...
>> > End Using
>> >> End Sub
>> >
>> > Which is basically the following in .NET 1.x:
>> >
>> > Dim myCustomer As New Customer
>> > Try
>> > DoSomething()
>> > Finally
>> > If myCustomer IsNot Nothing Then
>> > myCustomer.Dispose()
>> > End If
>> > End Try
>> >
>> > --
>> > Hope this helps
>> > Jay B. Harlow [MVP - Outlook]
>> > .NET Application Architect, Enthusiast, & Evangelist
>> > T.S. Bradley - http://www.tsbradley.net
>> >
>> >
>> > "Hao Jiang" <Hao (E-Mail Removed)> wrote in message
>> > news:4551F173-DAB8-4F74-AE61-(E-Mail Removed)...
>> >> Hi,
>> >>
>> >> I see in many MS example code that looks like this
>> >>
>> >> Public Sub Foo()
>> >> dim myCustomer as New Customer
>> >> ...
>> >> myCustomer.Dispose()
>> >> myCustomer = Nothing
>> >> End Sub
>> >>
>> >> I'm wondering if setting myCustomer = Nothing is necessary in this
>> >> case?
>> >> Since myCustomer is a private variable, once it goes out of scope at
>> >> the
>> >> next
>> >> line, the reference to the object should be released.
>> >>
>> >> Thanks.
>> >>
>> >> Hao
>> >
>>
>>
>>