re-initialize an object in same variable

[Wilfried Mestdagh]

Hi,

When I use same variable for a new created object, then whill the old one
destroyed by garbage collection, or do I first have to set it to null ?

eg:

SomeObject o = new SomeObject();
// and a while later:
o = new SomeObject();

or should I do:
o = null; // or call destructor? how?
o = new SomeObject();

--
rgds, Wilfried
http://www.mestdagh.biz

[Miha Markic [MVP C#]]

Hi Wilfried,

You should call Dispose, if that class supports it, before replacing the
instance.

--
Miha Markic [MVP C#] - RightHand .NET consulting & development
SLODUG - Slovene Developer Users Group
www.rthand.com

"Wilfried Mestdagh" <Wi**************@discussions.microsoft.com> wrote in
message news:0C**********************************@microsof t.com...

Hi,

When I use same variable for a new created object, then whill the old one
destroyed by garbage collection, or do I first have to set it to null ?

eg:

SomeObject o = new SomeObject();
// and a while later:
o = new SomeObject();

or should I do:
o = null; // or call destructor? how?
o = new SomeObject();

--
rgds, Wilfried
http://www.mestdagh.biz

[Joakim Karlsson]

There is no need to set the variable to null prior to changing it's
value. The only thing that matters to the garbage collector in this
scenario is that there no longer are any references to the instance that
was created first.

As to when the garbage collector actually collects the now unused
object, you don't know. It depends on how much more memory your
application is allocating.

As Miha said, if your object are referencing any resources that you need
to explicitly destroy at the time you stop referencing your object, you
should have the object implement IDispose and call that object's Dispose
method.

Regards,
Joakim

Miha Markic [MVP C#] wrote:

Hi Wilfried,

You should call Dispose, if that class supports it, before replacing the
instance.

[Wilfried Mestdagh]

Hi Miha,

You should call Dispose, if that class supports it, before replacing the
instance.

It dont supports it :( It is little class from my own. If I write a
destructor then it is not called. It is called only when I do a new into a
stack variable wich seems logical.

It does not allocate memory, but it holds some public variables calculated
at creation time. This means I have a memory leak when calling new 2 time?

How do I implement a Dispose method ? I read that a destructor cannot be
called just like that?

--
rgds, Wilfried
http://www.mestdagh.biz

[Joakim Karlsson]

Sorry, the interface to implement is named IDisposable, not IDispose as
I said.

The following article describes how to use it:

http://www.codeproject.com/csharp/IDispose.asp

Regards,
Joakim

Joakim Karlsson wrote:

There is no need to set the variable to null prior to changing it's
value. The only thing that matters to the garbage collector in this
scenario is that there no longer are any references to the instance that
was created first.

As to when the garbage collector actually collects the now unused
object, you don't know. It depends on how much more memory your
application is allocating.

As Miha said, if your object are referencing any resources that you need
to explicitly destroy at the time you stop referencing your object, you
should have the object implement IDispose and call that object's Dispose
method.

Regards,
Joakim

Miha Markic [MVP C#] wrote:

Hi Wilfried,

You should call Dispose, if that class supports it, before replacing
the instance.

[Willy Denoyette [MVP]]

What do you mean with " it holds public variables"? If these hold values,
those will be gone with the object when it gets collected. If they hold
references, those will get collected when the GC comes along too. Thers is
no leak, and there's no need to Dispose.

Willy.

"Wilfried Mestdagh" <Wi**************@discussions.microsoft.com> wrote in
message news:C4**********************************@microsof t.com...

Hi Miha,

You should call Dispose, if that class supports it, before replacing the
instance.

It dont supports it :( It is little class from my own. If I write a
destructor then it is not called. It is called only when I do a new into a
stack variable wich seems logical.

It does not allocate memory, but it holds some public variables calculated
at creation time. This means I have a memory leak when calling new 2 time?

How do I implement a Dispose method ? I read that a destructor cannot be
called just like that?

--
rgds, Wilfried
http://www.mestdagh.biz

[Miha Markic [MVP C#]]

Hi Wilfried,

I was generaly speaking. If the class implements IDisposable (Dispose
method) you should call it before loosing the instance. If it doesn't then
you don't need to call anything (well, actually depends on the class
implementation - well behaved classes would have IDisposable).
You need to implement IDisposable (and thus Dispose) only if you want to do
some clean up or close valuable resources.
In your case, you don't need to implement it because you don't hold any such
resource - that variable of yours will be collected by garbage collector
when all references to holding class are lost (when you assing new instance
to your variable o).

So, in your case, there is no need to do anything (call Dispose or set
variable to null) - just assign new instance.

--
Miha Markic [MVP C#] - RightHand .NET consulting & development
SLODUG - Slovene Developer Users Group
www.rthand.com

"Wilfried Mestdagh" <Wi**************@discussions.microsoft.com> wrote in
message news:C4**********************************@microsof t.com...

Hi Miha,

You should call Dispose, if that class supports it, before replacing the
instance.

It dont supports it :( It is little class from my own. If I write a
destructor then it is not called. It is called only when I do a new into a
stack variable wich seems logical.

It does not allocate memory, but it holds some public variables calculated
at creation time. This means I have a memory leak when calling new 2 time?

How do I implement a Dispose method ? I read that a destructor cannot be
called just like that?

--
rgds, Wilfried
http://www.mestdagh.biz