Dispose then set to nothing

[=?Utf-8?B?SGFvIEppYW5n?=]

Hi,

I see in many MS example code that looks like this

Public Sub Foo()
dim myCustomer as New Customer
...
myCustomer.Disp ose()
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

[=?UTF-8?B?R8O2cmFuIEFuZGVyc3Nvbg==?=]

Hao Jiang wrote:

Hi,

I see in many MS example code that looks like this

Public Sub Foo()
dim myCustomer as New Customer
...
myCustomer.Disp ose()
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

[Herfried K. Wagner [MVP]]

"Hao Jiang" <Hao Ji***@discussio ns.microsoft.co mschrieb:

Public Sub Foo()
dim myCustomer as New Customer
...
myCustomer.Disp ose()
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/>

[Jay B. Harlow [MVP - Outlook]]

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.Disp ose()
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 Ji***@discussio ns.microsoft.co mwrote in message
news:45******** *************** ***********@mic rosoft.com...

Hi,

I see in many MS example code that looks like this

Public Sub Foo()
dim myCustomer as New Customer
...
myCustomer.Disp ose()
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

[Cor Ligthert [MVP]]

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]" <Ja************ @tsbradley.nets chreef in
bericht news:eI******** ******@TK2MSFTN GP04.phx.gbl...

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.Disp ose()
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 Ji***@discussio ns.microsoft.co mwrote in message
news:45******** *************** ***********@mic rosoft.com...

>Hi,

I see in many MS example code that looks like this

Public Sub Foo()
dim myCustomer as New Customer
...
myCustomer.Disp ose()
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

[aaron.kempf]

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...@discussion s.microsoft.com >
wrote:

Hi,

I see in many MS example code that looks like this

Public Sub Foo()
dim myCustomer as New Customer
...
myCustomer.Disp ose()
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

[=?Utf-8?B?SGFvIEppYW5n?=]

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]" <Ja************ @tsbradley.nets chreef in
bericht news:eI******** ******@TK2MSFTN GP04.phx.gbl...

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.Disp ose()
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 Ji***@discussio ns.microsoft.co mwrote in message
news:45******** *************** ***********@mic rosoft.com...

Hi,

I see in many MS example code that looks like this

Public Sub Foo()
dim myCustomer as New Customer
...
myCustomer.Disp ose()
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

[Brian Gideon]

On Feb 26, 5:30 pm, Hao Jiang <Hao J...@discussion s.microsoft.com >
wrote:

Hi,

I see in many MS example code that looks like this

Public Sub Foo()
dim myCustomer as New Customer
...
myCustomer.Disp ose()
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

[Brian Gideon]

On Feb 27, 11:25 am, Hao Jiang <HaoJi...@discu ssions.microsof t.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.

[Cor Ligthert [MVP]]

Hao,

Thanks, I have sent it further

Cor

"Hao Jiang" <Ha******@discu ssions.microsof t.comschreef in bericht
news:FA******** *************** ***********@mic rosoft.com...

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]" <Ja************ @tsbradley.nets chreef in
bericht news:eI******** ******@TK2MSFTN GP04.phx.gbl...

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.Disp ose()
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 Ji***@discussio ns.microsoft.co mwrote in message
news:45******** *************** ***********@mic rosoft.com...
Hi,

I see in many MS example code that looks like this

Public Sub Foo()
dim myCustomer as New Customer
...
myCustomer.Disp ose()
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