Instances effecting each other?

[Daniel]

My previous thread got very large so here is my point again, but a better
example of my problem:

SceneChair chair = (SceneChair)_ob jMan.GetObject( (int)ObjectID.S eats);

chair.Position = GetSeatPosition (1);

chair.FrameNum = 1;

_objMan.AddToRe nderStack(chair );

SceneChair chair2 = new SceneChair();

chair2 = chair;

chair2.Position = GetSeatPosition (3);

chair2.FrameNum = 2;

_objMan.AddToRe nderStack(chair 2);

Ok in the above code when i debug, at the line chair2.Position both
instances are equal in data as you would expect.

Now when i go to the final _objMan.AddToRe nderStack line both the chair
instance and the chair2 instance framenumbers become 2. But i only changed
chair2's one so chair being a differenct instance shouldnt be effected
right?

The SceneChair chair2 = new SceneChair(); should have created a new memory
space and then when i changed chair2's framenum the memory allocated for
chair2 shoudl change while chair's remains the same. Am i right? So why do
they both change later on??? This is why when i add it to my stack they are
equal, as it is changing them as i said before while on the stack as if it
were the same instance.

[Lebesgue]

Your problem is here:

chair2 = chair

from this moment, you are changing the chair instance. The object that
chair2 was referencing after line chair2 = new SceneChair() went away,
because the actual object has lost its last reference (chair2 was its only
reference).
"Daniel" <Da*****@vestry online.com> wrote in message
news:%2******** ********@TK2MSF TNGP04.phx.gbl. ..

My previous thread got very large so here is my point again, but a better
example of my problem:

SceneChair chair = (SceneChair)_ob jMan.GetObject( (int)ObjectID.S eats);

chair.Position = GetSeatPosition (1);

chair.FrameNum = 1;

_objMan.AddToRe nderStack(chair );

SceneChair chair2 = new SceneChair();

chair2 = chair;

chair2.Position = GetSeatPosition (3);

chair2.FrameNum = 2;

_objMan.AddToRe nderStack(chair 2);

Ok in the above code when i debug, at the line chair2.Position both
instances are equal in data as you would expect.

Now when i go to the final _objMan.AddToRe nderStack line both the chair
instance and the chair2 instance framenumbers become 2. But i only changed
chair2's one so chair being a differenct instance shouldnt be effected
right?

The SceneChair chair2 = new SceneChair(); should have created a new memory
space and then when i changed chair2's framenum the memory allocated for
chair2 shoudl change while chair's remains the same. Am i right? So why do
they both change later on??? This is why when i add it to my stack they
are
equal, as it is changing them as i said before while on the stack as if it
were the same instance.

[Göran Andersson]

Daniel wrote:

My previous thread got very large so here is my point again, but a better
example of my problem:

SceneChair chair = (SceneChair)_ob jMan.GetObject( (int)ObjectID.S eats);

chair.Position = GetSeatPosition (1);

chair.FrameNum = 1;

_objMan.AddToRe nderStack(chair );

SceneChair chair2 = new SceneChair();

chair2 = chair;

chair2.Position = GetSeatPosition (3);

chair2.FrameNum = 2;

_objMan.AddToRe nderStack(chair 2);

Ok in the above code when i debug, at the line chair2.Position both
instances are equal in data as you would expect.
Not only in data. They are the same instance. You are not copying the
data of the object, but the reference to the object.
Now when i go to the final _objMan.AddToRe nderStack line both the chair
instance and the chair2 instance framenumbers become 2. But i only changed
chair2's one so chair being a differenct instance shouldnt be effected
right?
No, it isn't a different instance.
The SceneChair chair2 = new SceneChair(); should have created a new memory
space
Yes, it does. But you overwrite the reference to that new object, so
it's thrown away and never used.
and then when i changed chair2's framenum the memory allocated for
chair2 shoudl change while chair's remains the same. Am i right? So why do
they both change later on???
Not later on. As there is only one instance, it changes instantly when
you change it.
This is why when i add it to my stack they are
equal, as it is changing them as i said before while on the stack as if it
were the same instance.

That is because they *are* the same instance.

[Joanna Carter [TeamB]]

"Daniel" <Da*****@vestry online.com> a écrit dans le message de news:
%2************* ***@TK2MSFTNGP0 4.phx.gbl...

| SceneChair chair = (SceneChair)_ob jMan.GetObject( (int)ObjectID.S eats);
|
| chair.Position = GetSeatPosition (1);
|
| chair.FrameNum = 1;
|
| _objMan.AddToRe nderStack(chair );
|
| SceneChair chair2 = new SceneChair();

Here you assign chair2 to a new instance of SceneChair

| chair2 = chair;

Here you are assigning chair2 to chair, which is the first instance.

So now you have two references to the original chair object and the second
one that was held in chair2 is garbage collected.

Joanna

--
Joanna Carter [TeamB]
Consultant Software Engineer

[Daniel]

Thats the answer i was looking for.

I made that bit of code as a basic example buti think that is what is
happening anyway.

So in that case how can i take an instance in an array and create a new
instance with the same data?

I want to do this:

Object newInstance = _myList[1];

Where newInstance when changed does not affect _myList[1] after.

I always thought by using the new operator it solved this by allocating new
memory i didnt realise that the '=' sign copied the reference and not the
actual data.

Could you show me how to do this? What i dont understand is i do this kind
of thing all the time, the only difference here is that i am using List
instead of array, i preumse arrays create new instances and lists use the
reference?
"Göran Andersson" <gu***@guffa.co m> wrote in message
news:%2******** ********@TK2MSF TNGP05.phx.gbl. ..

Daniel wrote:

My previous thread got very large so here is my point again, but a better
example of my problem:

SceneChair chair = (SceneChair)_ob jMan.GetObject( (int)ObjectID.S eats);

chair.Position = GetSeatPosition (1);

chair.FrameNum = 1;

_objMan.AddToRe nderStack(chair );

SceneChair chair2 = new SceneChair();

chair2 = chair;

chair2.Position = GetSeatPosition (3);

chair2.FrameNum = 2;

_objMan.AddToRe nderStack(chair 2);

Ok in the above code when i debug, at the line chair2.Position both
instances are equal in data as you would expect.

Not only in data. They are the same instance. You are not copying the data
of the object, but the reference to the object.

Now when i go to the final _objMan.AddToRe nderStack line both the chair
instance and the chair2 instance framenumbers become 2. But i only
changed
chair2's one so chair being a differenct instance shouldnt be effected
right?

No, it isn't a different instance.

The SceneChair chair2 = new SceneChair(); should have created a new
memory
space

Yes, it does. But you overwrite the reference to that new object, so it's
thrown away and never used.

and then when i changed chair2's framenum the memory allocated for
chair2 shoudl change while chair's remains the same. Am i right? So why
do
they both change later on???

Not later on. As there is only one instance, it changes instantly when you
change it.

This is why when i add it to my stack they are
equal, as it is changing them as i said before while on the stack as if
it
were the same instance.

That is because they *are* the same instance.

[Lebesgue]

Implement ICloneable interface and call Clone on the instance you want to
copy. Also make sure you will not be returning "this" reference in the Clone
method implementation ;-)

"Daniel" <Da*****@vestry online.com> wrote in message
news:Or******** ********@TK2MSF TNGP05.phx.gbl. ..

Thats the answer i was looking for.

I made that bit of code as a basic example buti think that is what is
happening anyway.

So in that case how can i take an instance in an array and create a new
instance with the same data?

I want to do this:

Object newInstance = _myList[1];

Where newInstance when changed does not affect _myList[1] after.

I always thought by using the new operator it solved this by allocating
new memory i didnt realise that the '=' sign copied the reference and not
the actual data.

Could you show me how to do this? What i dont understand is i do this kind
of thing all the time, the only difference here is that i am using List
instead of array, i preumse arrays create new instances and lists use the
reference?
"Göran Andersson" <gu***@guffa.co m> wrote in message
news:%2******** ********@TK2MSF TNGP05.phx.gbl. ..

Daniel wrote:

My previous thread got very large so here is my point again, but a
better example of my problem:

SceneChair chair = (SceneChair)_ob jMan.GetObject( (int)ObjectID.S eats);

chair.Position = GetSeatPosition (1);

chair.FrameNum = 1;

_objMan.AddToRe nderStack(chair );

SceneChair chair2 = new SceneChair();

chair2 = chair;

chair2.Position = GetSeatPosition (3);

chair2.FrameNum = 2;

_objMan.AddToRe nderStack(chair 2);

Ok in the above code when i debug, at the line chair2.Position both
instances are equal in data as you would expect.

Not only in data. They are the same instance. You are not copying the
data of the object, but the reference to the object.

Now when i go to the final _objMan.AddToRe nderStack line both the chair
instance and the chair2 instance framenumbers become 2. But i only
changed
chair2's one so chair being a differenct instance shouldnt be effected
right?

No, it isn't a different instance.

The SceneChair chair2 = new SceneChair(); should have created a new
memory
space

Yes, it does. But you overwrite the reference to that new object, so it's
thrown away and never used.

and then when i changed chair2's framenum the memory allocated for
chair2 shoudl change while chair's remains the same. Am i right? So why
do
they both change later on???

Not later on. As there is only one instance, it changes instantly when
you change it.

This is why when i add it to my stack they are
equal, as it is changing them as i said before while on the stack as if
it
were the same instance.

That is because they *are* the same instance.

[Göran Andersson]

Daniel wrote:

Thats the answer i was looking for.

I made that bit of code as a basic example buti think that is what is
happening anyway.

So in that case how can i take an instance in an array and create a new
instance with the same data?

I want to do this:

Object newInstance = _myList[1];

Where newInstance when changed does not affect _myList[1] after.
As Lebesgue said, you should clone the object. Basically that means
creating a new instance and copy all the data to it.
I always thought by using the new operator it solved this by allocating new
memory i didnt realise that the '=' sign copied the reference and not the
actual data.

Could you show me how to do this? What i dont understand is i do this kind
of thing all the time, the only difference here is that i am using List
instead of array, i preumse arrays create new instances and lists use the
reference?
No. Instances are never created automatically. You must have been lucky
in the past. That, or you have a lot of potential bugs lurking in your
code...
"Göran Andersson" <gu***@guffa.co m> wrote in message
news:%2******** ********@TK2MSF TNGP05.phx.gbl. ..

Daniel wrote:

My previous thread got very large so here is my point again, but a better
example of my problem:

SceneChair chair = (SceneChair)_ob jMan.GetObject( (int)ObjectID.S eats);

chair.Position = GetSeatPosition (1);

chair.FrameNum = 1;

_objMan.AddToRe nderStack(chair );

SceneChair chair2 = new SceneChair();

chair2 = chair;

chair2.Position = GetSeatPosition (3);

chair2.FrameNum = 2;

_objMan.AddToRe nderStack(chair 2);

Ok in the above code when i debug, at the line chair2.Position both
instances are equal in data as you would expect.

Not only in data. They are the same instance. You are not copying the data
of the object, but the reference to the object.

Now when i go to the final _objMan.AddToRe nderStack line both the chair
instance and the chair2 instance framenumbers become 2. But i only
changed
chair2's one so chair being a differenct instance shouldnt be effected
right?

No, it isn't a different instance.

The SceneChair chair2 = new SceneChair(); should have created a new
memory
space

Yes, it does. But you overwrite the reference to that new object, so it's
thrown away and never used.

and then when i changed chair2's framenum the memory allocated for
chair2 shoudl change while chair's remains the same. Am i right? So why
do
they both change later on???

Not later on. As there is only one instance, it changes instantly when you
change it.

This is why when i add it to my stack they are
equal, as it is changing them as i said before while on the stack as if
it
were the same instance.

That is because they *are* the same instance.

[Daniel]

But now i am not sure how to create a new instance to do that with, i always
thought 'new' did this.

Is this right?

Clone()
{
Object myObj = new myObj();

myObj.x = this.x;
myObj.y = this.y;

return myObj;
}

Would the above return a clone not a reference?
"Göran Andersson" <gu***@guffa.co m> wrote in message
news:uN******** ******@TK2MSFTN GP03.phx.gbl...

Daniel wrote:

Thats the answer i was looking for.

I made that bit of code as a basic example buti think that is what is
happening anyway.

So in that case how can i take an instance in an array and create a new
instance with the same data?

I want to do this:

Object newInstance = _myList[1];

Where newInstance when changed does not affect _myList[1] after.

As Lebesgue said, you should clone the object. Basically that means
creating a new instance and copy all the data to it.

I always thought by using the new operator it solved this by allocating
new memory i didnt realise that the '=' sign copied the reference and not
the actual data.

Could you show me how to do this? What i dont understand is i do this
kind of thing all the time, the only difference here is that i am using
List instead of array, i preumse arrays create new instances and lists
use the reference?

No. Instances are never created automatically. You must have been lucky in
the past. That, or you have a lot of potential bugs lurking in your
code...

"Göran Andersson" <gu***@guffa.co m> wrote in message
news:%2******** ********@TK2MSF TNGP05.phx.gbl. ..

Daniel wrote:
My previous thread got very large so here is my point again, but a
better example of my problem:

SceneChair chair = (SceneChair)_ob jMan.GetObject( (int)ObjectID.S eats);

chair.Position = GetSeatPosition (1);

chair.FrameNum = 1;

_objMan.AddToRe nderStack(chair );

SceneChair chair2 = new SceneChair();

chair2 = chair;

chair2.Position = GetSeatPosition (3);

chair2.FrameNum = 2;

_objMan.AddToRe nderStack(chair 2);

Ok in the above code when i debug, at the line chair2.Position both
instances are equal in data as you would expect.
Not only in data. They are the same instance. You are not copying the
data of the object, but the reference to the object.

Now when i go to the final _objMan.AddToRe nderStack line both the chair
instance and the chair2 instance framenumbers become 2. But i only
changed
chair2's one so chair being a differenct instance shouldnt be effected
right?
No, it isn't a different instance.

The SceneChair chair2 = new SceneChair(); should have created a new
memory
space
Yes, it does. But you overwrite the reference to that new object, so
it's thrown away and never used.

and then when i changed chair2's framenum the memory allocated for
chair2 shoudl change while chair's remains the same. Am i right? So why
do
they both change later on???
Not later on. As there is only one instance, it changes instantly when
you change it.

This is why when i add it to my stack they are
equal, as it is changing them as i said before while on the stack as if
it
were the same instance.
That is because they *are* the same instance.

[Daniel]

Sorry following on from last example.....do i need to do this to make th
enew insatce?

object newObject = Activator.Creat eInstance(this. GetType());

"Göran Andersson" <gu***@guffa.co m> wrote in message
news:uN******** ******@TK2MSFTN GP03.phx.gbl...

Daniel wrote:

Thats the answer i was looking for.

I made that bit of code as a basic example buti think that is what is
happening anyway.

So in that case how can i take an instance in an array and create a new
instance with the same data?

I want to do this:

Object newInstance = _myList[1];

Where newInstance when changed does not affect _myList[1] after.

As Lebesgue said, you should clone the object. Basically that means
creating a new instance and copy all the data to it.

I always thought by using the new operator it solved this by allocating
new memory i didnt realise that the '=' sign copied the reference and not
the actual data.

Could you show me how to do this? What i dont understand is i do this
kind of thing all the time, the only difference here is that i am using
List instead of array, i preumse arrays create new instances and lists
use the reference?

No. Instances are never created automatically. You must have been lucky in
the past. That, or you have a lot of potential bugs lurking in your
code...

"Göran Andersson" <gu***@guffa.co m> wrote in message
news:%2******** ********@TK2MSF TNGP05.phx.gbl. ..

Daniel wrote:
My previous thread got very large so here is my point again, but a
better example of my problem:

SceneChair chair = (SceneChair)_ob jMan.GetObject( (int)ObjectID.S eats);

chair.Position = GetSeatPosition (1);

chair.FrameNum = 1;

_objMan.AddToRe nderStack(chair );

SceneChair chair2 = new SceneChair();

chair2 = chair;

chair2.Position = GetSeatPosition (3);

chair2.FrameNum = 2;

_objMan.AddToRe nderStack(chair 2);

Ok in the above code when i debug, at the line chair2.Position both
instances are equal in data as you would expect.
Not only in data. They are the same instance. You are not copying the
data of the object, but the reference to the object.

Now when i go to the final _objMan.AddToRe nderStack line both the chair
instance and the chair2 instance framenumbers become 2. But i only
changed
chair2's one so chair being a differenct instance shouldnt be effected
right?
No, it isn't a different instance.

The SceneChair chair2 = new SceneChair(); should have created a new
memory
space
Yes, it does. But you overwrite the reference to that new object, so
it's thrown away and never used.

and then when i changed chair2's framenum the memory allocated for
chair2 shoudl change while chair's remains the same. Am i right? So why
do
they both change later on???
Not later on. As there is only one instance, it changes instantly when
you change it.

This is why when i add it to my stack they are
equal, as it is changing them as i said before while on the stack as if
it
were the same instance.
That is because they *are* the same instance.

[Lebesgue]

You don't need to use Activator, new will suffice for creating new instance

"Daniel" <Da*****@vestry online.com> wrote in message
news:eM******** ********@TK2MSF TNGP02.phx.gbl. ..

Sorry following on from last example.....do i need to do this to make th
enew insatce?

object newObject = Activator.Creat eInstance(this. GetType());

"Göran Andersson" <gu***@guffa.co m> wrote in message
news:uN******** ******@TK2MSFTN GP03.phx.gbl...

Daniel wrote:

Thats the answer i was looking for.

I made that bit of code as a basic example buti think that is what is
happening anyway.

So in that case how can i take an instance in an array and create a new
instance with the same data?

I want to do this:

Object newInstance = _myList[1];

Where newInstance when changed does not affect _myList[1] after.

As Lebesgue said, you should clone the object. Basically that means
creating a new instance and copy all the data to it.

I always thought by using the new operator it solved this by allocating
new memory i didnt realise that the '=' sign copied the reference and
not the actual data.

Could you show me how to do this? What i dont understand is i do this
kind of thing all the time, the only difference here is that i am using
List instead of array, i preumse arrays create new instances and lists
use the reference?

No. Instances are never created automatically. You must have been lucky
in the past. That, or you have a lot of potential bugs lurking in your
code...

"Göran Andersson" <gu***@guffa.co m> wrote in message
news:%2******** ********@TK2MSF TNGP05.phx.gbl. ..
Daniel wrote:
> My previous thread got very large so here is my point again, but a
> better example of my problem:
>
> SceneChair chair = (SceneChair)_ob jMan.GetObject( (int)ObjectID.S eats);
>
> chair.Position = GetSeatPosition (1);
>
> chair.FrameNum = 1;
>
> _objMan.AddToRe nderStack(chair );
>
> SceneChair chair2 = new SceneChair();
>
> chair2 = chair;
>
> chair2.Position = GetSeatPosition (3);
>
> chair2.FrameNum = 2;
>
> _objMan.AddToRe nderStack(chair 2);
>
>
>
> Ok in the above code when i debug, at the line chair2.Position both
> instances are equal in data as you would expect.
Not only in data. They are the same instance. You are not copying the
data of the object, but the reference to the object.

> Now when i go to the final _objMan.AddToRe nderStack line both the
> chair
> instance and the chair2 instance framenumbers become 2. But i only
> changed
> chair2's one so chair being a differenct instance shouldnt be effected
> right?
No, it isn't a different instance.

> The SceneChair chair2 = new SceneChair(); should have created a new
> memory
> space
Yes, it does. But you overwrite the reference to that new object, so
it's thrown away and never used.

> and then when i changed chair2's framenum the memory allocated for
> chair2 shoudl change while chair's remains the same. Am i right? So
> why do
> they both change later on???
Not later on. As there is only one instance, it changes instantly when
you change it.

> This is why when i add it to my stack they are
> equal, as it is changing them as i said before while on the stack as
> if it
> were the same instance.
That is because they *are* the same instance.