formArray close / dispose issue

[Miro]

I have created myself an issue, and perhaps my idea wasn't as bright as I
thought it was originally.
If someone can help me figure out what the correct train of thought should
be - or if there is a solution to this one.

I created a dummy mdi app.
In the main form ( frmMainScreen ) I created a variable as such:
<written in notepad to trim everything down>

Public Shared frmFormsOpen() As frmMyTestForm

Now, in a totally seperate sub form opend from the main form I do this on a
button click:

LengthOfGames = (frmMainScreen. frmFormsOpen.Le ngth - 1)
ReDim Preserve frmMainScreen.f rmFormsOpen(Len gthOfGames)

frmMainScreen.f rmFormsOpen(Len gthOfGames) = New frmMyTestForm
frmMainScreen.f rmFormsOpen(Len gthOfGames).Mdi Parent = Me.MdiParent
'Remember that this form is also an mdi child of the main form.
'Set my own property for later use
frmMainScreen.f rmFormsOpen(Len gthOfGames).Gam eID = anIntegerValue

frmMainScreen.f rmFormsOpen(Len gthOfGames).Sho w()

'Works Great
So in other code on other child forms forms I can do stuff like this:

For Each SearchForm As frmMyTestForm In
frmMainScreen.f rmFormsOpen
If SearchForm.Game ID = mytestID Then 'mytestID is set to a
value from something else
SearchForm.Brin gToFront()
Exit For
End If
Next


My problem is this:

where do i actually remove the array element when the form is closed. I do
not want it to stay in the array.
I do not think I can do it in the _FormClosed of the
frmMainScreen.f rmFormsOpen(Len gthOfGames)._Fo rmClosed
because I am actually in the form itself still - so I am assuming I cannot
kill the object when I am still using the object.
( im trying to kill myself from myself ).

That is my issue I have created myself and I was wondering if someone can
point me in the right direction on how to get around this issue.

Thanks,

Miro

[Armin Zingler]

Re: formArray close / dispose issue

"Miro" <miro@beero.com schrieb

where do i actually remove the array element when the form is
closed. I do not want it to stay in the array.

Do yourself a favor and use a List(Of frmMyTestForm) instead of the array.
(which VB version?) Safes you from item shifting and redimming.

I do not think I can do it in the _FormClosed of the
frmMainScreen.f rmFormsOpen(Len gthOfGames)._Fo rmClosed
because I am actually in the form itself still - so I am assuming I
cannot kill the object when I am still using the object.
( im trying to kill myself from myself ).

You don't kill anything by removing one reference. You can safely remove the
item from the list in the FormClosed event. The object on which the current
method is executed is never destroyed.


Armin

[Miro]

Re: formArray close / dispose issue

Its vb 2008

Thank you for the post.
I was under the impression - since I am 'sitting' in the object still during
_FormClose then I cannot Remove my object from underneith my feet.

Im assuming then by your statement

>The object on which the current method is executed is never destroyed.

That once I leave the form and it does close - it will be destroyed in the
background - I dont need to run anything else?

I will google and search up "List" to use a list instead of an array.

Thank you,

Miro

"Armin Zingler" <az.nospam@free net.dewrote in message
news:ub7GnmXOJH A.1164@TK2MSFTN GP02.phx.gbl...

"Miro" <miro@beero.com schrieb

>where do i actually remove the array element when the form is
>closed. I do not want it to stay in the array.

>
Do yourself a favor and use a List(Of frmMyTestForm) instead of the array.
(which VB version?) Safes you from item shifting and redimming.
>

>I do not think I can do it in the _FormClosed of the
>frmMainScreen. frmFormsOpen(Le ngthOfGames)._F ormClosed
>because I am actually in the form itself still - so I am assuming I
>cannot kill the object when I am still using the object.
>( im trying to kill myself from myself ).

>
You don't kill anything by removing one reference. You can safely remove
the
item from the list in the FormClosed event. The object on which the
current method is executed is never destroyed.
>
>
Armin
>

[Armin Zingler]

Re: formArray close / dispose issue

"Miro" <miro@beero.com schrieb

Im assuming then by your statement

>>The object on which the current method is executed is never destroyed.

That once I leave the form and it does close - it will be destroyed in the
background - I dont need to run anything else?

Yes, nothing else is required.

I will google and search up "List" to use a list instead of an array.

Not required to google - look in the object browser. It's
System.Collecti ons.Generic.Lis t(Of T)

see also:

http://msdn.microsoft.com/en-us/library/41107z8a.aspx

Armin

[Cor Ligthert[MVP]]

Re: formArray close / dispose issue

Miro,

You can find all the mdi forms by using
\\\
me.MDIParent.MD IChildren
///

http://msdn.microsoft.com/en-us/library/system.windows.forms.form.mdichildren.aspx

Probably much easier,

Cor


"Miro" <miro@beero.com schreef in bericht
news:Osau%23rWO JHA.3732@TK2MSF TNGP03.phx.gbl. ..

>I have created myself an issue, and perhaps my idea wasn't as bright as I
>thought it was originally.
If someone can help me figure out what the correct train of thought should
be - or if there is a solution to this one.
>
I created a dummy mdi app.
In the main form ( frmMainScreen ) I created a variable as such:
<written in notepad to trim everything down>
>
Public Shared frmFormsOpen() As frmMyTestForm
>
Now, in a totally seperate sub form opend from the main form I do this on
a button click:
>
LengthOfGames = (frmMainScreen. frmFormsOpen.Le ngth - 1)
ReDim Preserve frmMainScreen.f rmFormsOpen(Len gthOfGames)
>
frmMainScreen.f rmFormsOpen(Len gthOfGames) = New frmMyTestForm
frmMainScreen.f rmFormsOpen(Len gthOfGames).Mdi Parent = Me.MdiParent
'Remember that this form is also an mdi child of the main form.
'Set my own property for later use
frmMainScreen.f rmFormsOpen(Len gthOfGames).Gam eID = anIntegerValue
>
frmMainScreen.f rmFormsOpen(Len gthOfGames).Sho w()
>
'Works Great
So in other code on other child forms forms I can do stuff like this:
>
For Each SearchForm As frmMyTestForm In
frmMainScreen.f rmFormsOpen
If SearchForm.Game ID = mytestID Then 'mytestID is set to a
value from something else
SearchForm.Brin gToFront()
Exit For
End If
Next
>
>
My problem is this:
>
where do i actually remove the array element when the form is closed. I
do not want it to stay in the array.
I do not think I can do it in the _FormClosed of the
frmMainScreen.f rmFormsOpen(Len gthOfGames)._Fo rmClosed
because I am actually in the form itself still - so I am assuming I cannot
kill the object when I am still using the object.
( im trying to kill myself from myself ).
>
That is my issue I have created myself and I was wondering if someone can
point me in the right direction on how to get around this issue.
>
Thanks,
>
Miro
>
>
>

[Jack Jackson]

Re: formArray close / dispose issue

You are confusing removing a reference to an object from a list with
destruction of the object.

An object can have many references. Removing those references does
nothing other than, when all references have been removed, make the
object available for garbage collection. It does not cause the object
to be destroyed.

And as Armin said, please don't use arrays for this. List (Of T) is
much better.

On Tue, 28 Oct 2008 23:57:20 -0400, "Miro" <miro@beero.com wrote:

>Its vb 2008
>
>Thank you for the post.
>I was under the impression - since I am 'sitting' in the object still during
>_FormClose then I cannot Remove my object from underneith my feet.
>
>Im assuming then by your statement

>>The object on which the current method is executed is never destroyed.

>That once I leave the form and it does close - it will be destroyed in the
>background - I dont need to run anything else?
>
>I will google and search up "List" to use a list instead of an array.
>
>Thank you,
>
>Miro
>
>"Armin Zingler" <az.nospam@free net.dewrote in message
>news:ub7GnmXOJ HA.1164@TK2MSFT NGP02.phx.gbl.. .

>"Miro" <miro@beero.com schrieb

>>where do i actually remove the array element when the form is
>>closed. I do not want it to stay in the array.

>>
>Do yourself a favor and use a List(Of frmMyTestForm) instead of the array.
>(which VB version?) Safes you from item shifting and redimming.
>>

>>I do not think I can do it in the _FormClosed of the
>>frmMainScreen .frmFormsOpen(L engthOfGames)._ FormClosed
>>because I am actually in the form itself still - so I am assuming I
>>cannot kill the object when I am still using the object.
>>( im trying to kill myself from myself ).

>>
>You don't kill anything by removing one reference. You can safely remove
>the
>item from the list in the FormClosed event. The object on which the
>current method is executed is never destroyed.
>>
>>
>Armin
>>

[Miro]

Re: formArray close / dispose issue

Thank you -
I have changed it to use the List(Of T) and it works great and 10x easier.

I used an array because of my old dos day programming - arrays is all we
had.

Miro

"Armin Zingler" <az.nospam@free net.dewrote in message
news:ej2Ja1XOJH A.1488@TK2MSFTN GP03.phx.gbl...

"Miro" <miro@beero.com schrieb

>Im assuming then by your statement

>>>The object on which the current method is executed is never destroyed.

>That once I leave the form and it does close - it will be destroyed in
>the
>background - I dont need to run anything else?

>
Yes, nothing else is required.
>

>I will google and search up "List" to use a list instead of an array.

>
Not required to google - look in the object browser. It's
System.Collecti ons.Generic.Lis t(Of T)
>
see also:

http://msdn.microsoft.com/en-us/library/41107z8a.aspx

>
>
Armin
>

[Miro]

Re: formArray close / dispose issue

I see,

I was the understanding that if i say
dim bla as new form1

then I was under the impression the object instantiated and the object
exists in bla which was dim'd here.

To 'remove' it from this 'dim' would be pulling the rug from under me.

As I understand your comment - the object "REFERENCE" is dim'd here, but the
actaul object exists somewhere else, so I can
"undim" my bla without worries. ( if undim was a word ) but basically
remove it from bla.

Miro

"Jack Jackson" <jjackson@cinno vations.netwrot e in message
news:sj2hg493kp ktrv5vjqr06b6a8 r8tab41gv@4ax.c om...

You are confusing removing a reference to an object from a list with
destruction of the object.
>
An object can have many references. Removing those references does
nothing other than, when all references have been removed, make the
object available for garbage collection. It does not cause the object
to be destroyed.
>
And as Armin said, please don't use arrays for this. List (Of T) is
much better.
>
On Tue, 28 Oct 2008 23:57:20 -0400, "Miro" <miro@beero.com wrote:
>

>>Its vb 2008
>>
>>Thank you for the post.
>>I was under the impression - since I am 'sitting' in the object still
>>during
>>_FormClose then I cannot Remove my object from underneith my feet.
>>
>>Im assuming then by your statement

>>>The object on which the current method is executed is never destroyed.

>>That once I leave the form and it does close - it will be destroyed in the
>>background - I dont need to run anything else?
>>
>>I will google and search up "List" to use a list instead of an array.
>>
>>Thank you,
>>
>>Miro
>>
>>"Armin Zingler" <az.nospam@free net.dewrote in message
>>news:ub7GnmXO JHA.1164@TK2MSF TNGP02.phx.gbl. ..

>>"Miro" <miro@beero.com schrieb
>>>where do i actually remove the array element when the form is
>>>closed. I do not want it to stay in the array.
>>>
>>Do yourself a favor and use a List(Of frmMyTestForm) instead of the
>>array.
>>(which VB version?) Safes you from item shifting and redimming.
>>>
>>>I do not think I can do it in the _FormClosed of the
>>>frmMainScree n.frmFormsOpen( LengthOfGames). _FormClosed
>>>because I am actually in the form itself still - so I am assuming I
>>>cannot kill the object when I am still using the object.
>>>( im trying to kill myself from myself ).
>>>
>>You don't kill anything by removing one reference. You can safely remove
>>the
>>item from the list in the FormClosed event. The object on which the
>>current method is executed is never destroyed.
>>>
>>>
>>Armin
>>>

[Miro]

Re: formArray close / dispose issue

If I only had your brain to pick before I start to code :-)

Thanks,

Miro

"Cor Ligthert[MVP]" <notmyfirstname @planet.nlwrote in message
news:uJ0%23R7aO JHA.4332@TK2MSF TNGP06.phx.gbl. ..

Miro,
>
You can find all the mdi forms by using
\\\
me.MDIParent.MD IChildren
///
>

http://msdn.microsoft.com/en-us/library/system.windows.forms.form.mdichildren.aspx

>
Probably much easier,
>
Cor
>
>
"Miro" <miro@beero.com schreef in bericht
news:Osau%23rWO JHA.3732@TK2MSF TNGP03.phx.gbl. ..

>>I have created myself an issue, and perhaps my idea wasn't as bright as I
>>thought it was originally.
>If someone can help me figure out what the correct train of thought
>should be - or if there is a solution to this one.
>>
>I created a dummy mdi app.
>In the main form ( frmMainScreen ) I created a variable as such:
><written in notepad to trim everything down>
>>
>Public Shared frmFormsOpen() As frmMyTestForm
>>
>Now, in a totally seperate sub form opend from the main form I do this on
>a button click:
>>
>LengthOfGame s = (frmMainScreen. frmFormsOpen.Le ngth - 1)
>ReDim Preserve frmMainScreen.f rmFormsOpen(Len gthOfGames)
>>
>frmMainScreen. frmFormsOpen(Le ngthOfGames) = New frmMyTestForm
>frmMainScreen. frmFormsOpen(Le ngthOfGames).Md iParent = Me.MdiParent
>'Remember that this form is also an mdi child of the main form.
>'Set my own property for later use
>frmMainScreen. frmFormsOpen(Le ngthOfGames).Ga meID = anIntegerValue
>>
>frmMainScreen. frmFormsOpen(Le ngthOfGames).Sh ow()
>>
>'Works Great
>So in other code on other child forms forms I can do stuff like this:
>>
> For Each SearchForm As frmMyTestForm In
>frmMainScreen. frmFormsOpen
> If SearchForm.Game ID = mytestID Then 'mytestID is set to a
>value from something else
> SearchForm.Brin gToFront()
> Exit For
> End If
> Next
>>
>>
>My problem is this:
>>
>where do i actually remove the array element when the form is closed. I
>do not want it to stay in the array.
>I do not think I can do it in the _FormClosed of the
>frmMainScreen. frmFormsOpen(Le ngthOfGames)._F ormClosed
>because I am actually in the form itself still - so I am assuming I
>cannot kill the object when I am still using the object.
>( im trying to kill myself from myself ).
>>
>That is my issue I have created myself and I was wondering if someone can
>point me in the right direction on how to get around this issue.
>>
>Thanks,
>>
>Miro
>>
>>
>>

>
>

[Jack Jackson]

Re: formArray close / dispose issue

Making a variable no longer point at an object does not "pull the
rug". When all references to an object go away, the object becomes
eligible to be garbage collected at some time in the future.

Forms are a little different in that the framework keeps track of them
and has a reference to all open forms (Application.Op enForms), so even
if you clear your reference there is still one being held by the
framework.

For example:

Public Class MyClass
Public A As Integer = 0
End Class

Dim x As New MyClass ' There is one reference to an instance
' of MyClass
Dim y as MyClass = x ' Now there are two references
' to the instance
x = Nothing ' Now there is one reference (y)
y = Nothing ' Now there are no references and
' the instance is eligible for garbage
' collection.

On Thu, 30 Oct 2008 10:59:30 -0400, "Miro" <miro@beero.com wrote:

>I see,
>
>I was the understanding that if i say
>dim bla as new form1
>
>then I was under the impression the object instantiated and the object
>exists in bla which was dim'd here.
>
>To 'remove' it from this 'dim' would be pulling the rug from under me.
>
>As I understand your comment - the object "REFERENCE" is dim'd here, but the
>actaul object exists somewhere else, so I can
>"undim" my bla without worries. ( if undim was a word ) but basically
>remove it from bla.
>
>Miro
>
>"Jack Jackson" <jjackson@cinno vations.netwrot e in message
>news:sj2hg493k pktrv5vjqr06b6a 8r8tab41gv@4ax. com...

>You are confusing removing a reference to an object from a list with
>destruction of the object.
>>
>An object can have many references. Removing those references does
>nothing other than, when all references have been removed, make the
>object available for garbage collection. It does not cause the object
>to be destroyed.
>>
>And as Armin said, please don't use arrays for this. List (Of T) is
>much better.
>>
>On Tue, 28 Oct 2008 23:57:20 -0400, "Miro" <miro@beero.com wrote:
>>

>>>Its vb 2008
>>>
>>>Thank you for the post.
>>>I was under the impression - since I am 'sitting' in the object still
>>>during
>>>_FormClose then I cannot Remove my object from underneith my feet.
>>>
>>>Im assuming then by your statement
>>>>The object on which the current method is executed is never destroyed.
>>>That once I leave the form and it does close - it will be destroyed in the
>>>background - I dont need to run anything else?
>>>
>>>I will google and search up "List" to use a list instead of an array.
>>>
>>>Thank you,
>>>
>>>Miro
>>>
>>>"Armin Zingler" <az.nospam@free net.dewrote in message
>>>news:ub7GnmX OJHA.1164@TK2MS FTNGP02.phx.gbl ...
>>>"Miro" <miro@beero.com schrieb
>>>>where do i actually remove the array element when the form is
>>>>closed. I do not want it to stay in the array.
>>>>
>>>Do yourself a favor and use a List(Of frmMyTestForm) instead of the
>>>array.
>>>(which VB version?) Safes you from item shifting and redimming.
>>>>
>>>>I do not think I can do it in the _FormClosed of the
>>>>frmMainScre en.frmFormsOpen (LengthOfGames) ._FormClosed
>>>>because I am actually in the form itself still - so I am assuming I
>>>>cannot kill the object when I am still using the object.
>>>>( im trying to kill myself from myself ).
>>>>
>>>You don't kill anything by removing one reference. You can safely remove
>>>the
>>>item from the list in the FormClosed event. The object on which the
>>>current method is executed is never destroyed.
>>>>
>>>>
>>>Armin
>>>>

[Miro]

Re: formArray close / dispose issue

Thank you - excellent example for me to understand. -makes perfect sense
now.

I appreciate your time.

Thank you again,

Miro

"Jack Jackson" <jjackson@cinno vations.netwrot e in message
news:64tjg4t86o uqp8eg9cvh40dmo 764hlcvd2@4ax.c om...

Making a variable no longer point at an object does not "pull the
rug". When all references to an object go away, the object becomes
eligible to be garbage collected at some time in the future.
>
Forms are a little different in that the framework keeps track of them
and has a reference to all open forms (Application.Op enForms), so even
if you clear your reference there is still one being held by the
framework.
>
For example:
>
Public Class MyClass
Public A As Integer = 0
End Class
>
Dim x As New MyClass ' There is one reference to an instance
' of MyClass
Dim y as MyClass = x ' Now there are two references
' to the instance
x = Nothing ' Now there is one reference (y)
y = Nothing ' Now there are no references and
' the instance is eligible for garbage
' collection.
>
On Thu, 30 Oct 2008 10:59:30 -0400, "Miro" <miro@beero.com wrote:
>

>>I see,
>>
>>I was the understanding that if i say
>>dim bla as new form1
>>
>>then I was under the impression the object instantiated and the object
>>exists in bla which was dim'd here.
>>
>>To 'remove' it from this 'dim' would be pulling the rug from under me.
>>
>>As I understand your comment - the object "REFERENCE" is dim'd here, but
>>the
>>actaul object exists somewhere else, so I can
>>"undim" my bla without worries. ( if undim was a word ) but basically
>>remove it from bla.
>>
>>Miro
>>
>>"Jack Jackson" <jjackson@cinno vations.netwrot e in message
>>news:sj2hg493 kpktrv5vjqr06b6 a8r8tab41gv@4ax .com...

>>You are confusing removing a reference to an object from a list with
>>destruction of the object.
>>>
>>An object can have many references. Removing those references does
>>nothing other than, when all references have been removed, make the
>>object available for garbage collection. It does not cause the object
>>to be destroyed.
>>>
>>And as Armin said, please don't use arrays for this. List (Of T) is
>>much better.
>>>
>>On Tue, 28 Oct 2008 23:57:20 -0400, "Miro" <miro@beero.com wrote:
>>>
>>>>Its vb 2008
>>>>
>>>>Thank you for the post.
>>>>I was under the impression - since I am 'sitting' in the object still
>>>>during
>>>>_FormClos e then I cannot Remove my object from underneith my feet.
>>>>
>>>>Im assuming then by your statement
>>>>>The object on which the current method is executed is never destroyed.
>>>>That once I leave the form and it does close - it will be destroyed in
>>>>the
>>>>backgroun d - I dont need to run anything else?
>>>>
>>>>I will google and search up "List" to use a list instead of an array.
>>>>
>>>>Thank you,
>>>>
>>>>Miro
>>>>
>>>>"Armin Zingler" <az.nospam@free net.dewrote in message
>>>>news:ub7Gnm XOJHA.1164@TK2M SFTNGP02.phx.gb l...
>>>>"Miro" <miro@beero.com schrieb
>>>>>where do i actually remove the array element when the form is
>>>>>closed. I do not want it to stay in the array.
>>>>>
>>>>Do yourself a favor and use a List(Of frmMyTestForm) instead of the
>>>>array.
>>>>(which VB version?) Safes you from item shifting and redimming.
>>>>>
>>>>>I do not think I can do it in the _FormClosed of the
>>>>>frmMainScr een.frmFormsOpe n(LengthOfGames )._FormClosed
>>>>>because I am actually in the form itself still - so I am assuming I
>>>>>cannot kill the object when I am still using the object.
>>>>>( im trying to kill myself from myself ).
>>>>>
>>>>You don't kill anything by removing one reference. You can safely
>>>>remove
>>>>the
>>>>item from the list in the FormClosed event. The object on which the
>>>>current method is executed is never destroyed.
>>>>>
>>>>>
>>>>Armin
>>>>>