VB threads

[wally]

Does anyone have an example running using threads in vb.net? I would like
to see a complete example so that I can understand what is going on with
the code that I have running.

Wally

[Govind_kanshi]

A very simple sample,
A thread executes a function while the main thread listens for keyboard
input and quits when you enter q and hot Enter.

Systems.Threading provides the base Thread class.

The way thread is assigned what to execute is provided by AddressOf operator
which gets the function pointer from the function signature.

'----------------------------------------------------------
Imports System
Imports System.Threading

Namespace Sample
Module TestThread
private m_counter as Integer
private MAXINT as Integer = 10000

Sub DoCount()
While(1)
Console.WriteLine(m_counter)
m_counter = m_counter + 1

if m_counter = MAXINT then
m_counter = 1
End if
End While
End Sub

Shared Sub Main()

Dim i as Integer
Dim tThread as Thread
Dim c as Char

c = CChar("c")


tThread = new Thread(AddressOf DoCount)


tThread.Start
While ( Not (c = CChar("q")) )
i = Console.Read()
c = CChar(i)

End While
tThread.Stop
End Sub
End Module
End Namespace
'----------------------------------------------------





"wally" <wallym@mindspring.com> wrote in message
news:398b0abe$1@news.devx.com...
>
> Does anyone have an example running using threads in vb.net? I would like
> to see a complete example so that I can understand what is going on with
> the code that I have running.
>
> Wally

[Thomas Eyde]

This is a joke, right? Or..?

I thought the AddressOf operator worked only on methods in a .bas/modeule
and not on those in a class. Or has that changed in VB.Net?

This mechanics is slightly better than the good old timer approach, but not
very OO.

Please tell me the Thread object supports classes and use one or both kinds
of inheritance to achieve it

--
/Thomas
thomas.eyde@eunet.no


Govind_kanshi <Govind_kanshi@email.msn.com> wrote in message
news:398d1833@news.devx.com...
> A very simple sample,
> A thread executes a function while the main thread listens for keyboard
> input and quits when you enter q and hot Enter.
>
> Systems.Threading provides the base Thread class.
>
> The way thread is assigned what to execute is provided by AddressOf
operator
> which gets the function pointer from the function signature.
>
> '----------------------------------------------------------
> Imports System
> Imports System.Threading
>
> Namespace Sample
> Module TestThread
> private m_counter as Integer
> private MAXINT as Integer = 10000
>
> Sub DoCount()
> While(1)
> Console.WriteLine(m_counter)
> m_counter = m_counter + 1
>
> if m_counter = MAXINT then
> m_counter = 1
> End if
> End While
> End Sub
>
> Shared Sub Main()
>
> Dim i as Integer
> Dim tThread as Thread
> Dim c as Char
>
> c = CChar("c")
>
>
> tThread = new Thread(AddressOf DoCount)
>
>
> tThread.Start
> While ( Not (c = CChar("q")) )
> i = Console.Read()
> c = CChar(i)
>
> End While
> tThread.Stop
> End Sub
> End Module
> End Namespace
> '----------------------------------------------------
>
>
>
>
>
> "wally" <wallym@mindspring.com> wrote in message
> news:398b0abe$1@news.devx.com...
> >
> > Does anyone have an example running using threads in vb.net? I would
like
> > to see a complete example so that I can understand what is going on with
> > the code that I have running.
> >
> > Wally
>
>

[Govind_kanshi]

I think you are talking of the "runnable" Interface ? Well I was trying
to find that too without much success.

The AddressOf method can get the offset to the classes too, so this method
can be get a ref to fn in a class theoratically (I have not tested that)

from docs
"
Creating a new instance of a System.Threading.Thread object can create new
managed threads. The constructor for System.Threading.Thread takes, as its
only parameter, a Thread Delegate.

A delegate is an object that acts as reference to a method on another class.
A thread delegate is a special type of delegate that references a method
that will be executed by a new thread.

"


"Thomas Eyde" <thomas.eyde@eunet.no> wrote in message
news:398ddeba$1@news.devx.com...
> This is a joke, right? Or..?
>
> I thought the AddressOf operator worked only on methods in a .bas/modeule
> and not on those in a class. Or has that changed in VB.Net?
>
> This mechanics is slightly better than the good old timer approach, but
not
> very OO.
>
> Please tell me the Thread object supports classes and use one or both
kinds
> of inheritance to achieve it
>
> --
> /Thomas
> thomas.eyde@eunet.no
>
>
> Govind_kanshi <Govind_kanshi@email.msn.com> wrote in message
> news:398d1833@news.devx.com...
> > A very simple sample,
> > A thread executes a function while the main thread listens for keyboard
> > input and quits when you enter q and hot Enter.
> >
> > Systems.Threading provides the base Thread class.
> >
> > The way thread is assigned what to execute is provided by AddressOf
> operator
> > which gets the function pointer from the function signature.
> >
> > '----------------------------------------------------------
> > Imports System
> > Imports System.Threading
> >
> > Namespace Sample
> > Module TestThread
> > private m_counter as Integer
> > private MAXINT as Integer = 10000
> >
> > Sub DoCount()
> > While(1)
> > Console.WriteLine(m_counter)
> > m_counter = m_counter + 1
> >
> > if m_counter = MAXINT then
> > m_counter = 1
> > End if
> > End While
> > End Sub
> >
> > Shared Sub Main()
> >
> > Dim i as Integer
> > Dim tThread as Thread
> > Dim c as Char
> >
> > c = CChar("c")
> >
> >
> > tThread = new Thread(AddressOf DoCount)
> >
> >
> > tThread.Start
> > While ( Not (c = CChar("q")) )
> > i = Console.Read()
> > c = CChar(i)
> >
> > End While
> > tThread.Stop
> > End Sub
> > End Module
> > End Namespace
> > '----------------------------------------------------
> >
> >
> >
> >
> >
> > "wally" <wallym@mindspring.com> wrote in message
> > news:398b0abe$1@news.devx.com...
> > >
> > > Does anyone have an example running using threads in vb.net? I would
> like
> > > to see a complete example so that I can understand what is going on
with
> > > the code that I have running.
> > >
> > > Wally
> >
> >
>
>

[James Foxall]

"Thomas Eyde" <thomas.eyde@eunet.no> wrote:
>This is a joke, right? Or..?
>
>I thought the AddressOf operator worked only on methods in a .bas/modeule
>and not on those in a class. Or has that changed in VB.Net?

You can use AddressOf in a class module now. Not only that, I was told (in
a session at the PDC I thing) that you can now call functions without your
own project using the address returned by AddressOf.

James Foxall

[James Foxall]

>The AddressOf method can get the offset to the classes too, so this method
>can be get a ref to fn in a class theoratically (I have not tested that)

Actually, you'll see AddressOf used in classes a lot - it's used in the code
that gets automatically generated to create a form at runtime to hook up
event handlers. It's pretty cool stuff, at least to me.

James

[Bill McCarthy]

"James Foxall" <jamesf@tigerpawsoftware.com> wrote in message
news:398e1d28$1@news.devx.com...
>
> "Thomas Eyde" <thomas.eyde@eunet.no> wrote:
> >This is a joke, right? Or..?
> >
> >I thought the AddressOf operator worked only on methods in a .bas/modeule
> >and not on those in a class. Or has that changed in VB.Net?
>
> You can use AddressOf in a class module now. Not only that, I was told (in
> a session at the PDC I thing) that you can now call functions without your
> own project using the address returned by AddressOf.
>

Yeh, but it makes me wonder how the instance of the class is handled by the
garbage collection, as I can't see the GC being able to know that an
external dll has got a reference to a class's function. Hmm.. might have to
do some crash testing on that one.. <g>

[Michael \(michka\) Kaplan]

(and for people who want to do it in VB6, methods now exist for that sort of
thing <g>).

--
MichKa

random junk of dubious value at the multilingual
http://www.trigeminal.com/ and a new book on
i18N in VB at http://www.trigeminal.com/michka.asp

"James Foxall" <jamesf@tigerpawsoftware.com> wrote in message
news:398e1e1f$1@news.devx.com...
>
> >The AddressOf method can get the offset to the classes too, so this
method
> >can be get a ref to fn in a class theoratically (I have not tested that)
>
> Actually, you'll see AddressOf used in classes a lot - it's used in the
code
> that gets automatically generated to create a form at runtime to hook up
> event handlers. It's pretty cool stuff, at least to me.
>
> James
>

[James Foxall]

>Yeh, but it makes me wonder how the instance of the class is handled by the
garbage collection, as I can't see the GC being able to know that an external
dll has got a reference to a class's function. Hmm.. might have to do some
crash testing on that one.. <g>

Wow, Bill, that is a thought. I haven't got that far anyway. <g> I had a
bizzare deal happen to me today. I placed a splitter control on a form, but
did not dock the control to an edge. For that matter, I don't believe it
docked itself either. I then went into the code for the Win Form to dig about
a bit. When I tried to switch back to view the interface of the frm, I got
an error about the splitter control having to be docked to an edge, and that
I couldn't view the form designer until I corrected this problem!!! As it
turned out, I had no way to correct the problem (that I could come up with
anyway) without viewing the Win Form in design view, since the code within
the module is actually used to build the form at runtime. Circular problem
and a New Project! Ouch!

Another wierd thing, this one related to AddressOf. When you double-click
a control you get the default event for the control (such as Click for a
command button). .Net has been kind enough to add the code that hooks the
control and uses AddressOf to point the hook to the new procdure. If you
come back later and delete the procedure (not sure if it has to have code
in it or not), Visual Basic gives you a compile error when you attempt to
run the project, because it doesn't automatically delete the statement that
performs the hook! The statement with AddressOf is left holding an invalid
function reference, so your project won't compile.

There sure is a lot more to watch out for, even when doing simple things
compared to Visual Basic 6. But there sure is a LOT more functiolity.

James Foxall

[James Foxall]

"Michael \(michka\) Kaplan" <former_mvp@spamfree.trigeminal.nospam.com> wrote:
>(and for people who want to do it in VB6, methods now exist for that sort
of
>thing <g>).

Like keeping track of hooked user-controls in an array or linked list within
a Class module, or is there a better way? <Do tell! <g>>

James Foxall

[Govind_kanshi]

Let us take a wild guess and wise listeners fill the holes or blow new ones
?

Looking at the code generated you can see the ldftn/ldvirtftn is used to
load the
function pointer to the stack.
Going through the assembler's guide, looks like ngwssdk supports the
function pointers and they are not objects like the delegates ( actually if
you see the docs they mention to use a delegate for threadstart. But
obviously in VB that is not possible (?).

So we have to instantiate the class containing our function and we can get
the address of the function (which makes sense unless you have static
methods)

So the question is how would GC know who is using the one of the
instance/static functions via a pointer.

GC knows about the base class and it also knows the variable (thread) which
points to an instance of function of class or a static member function.
So that should be easy,.... I stand to be corrected. So its graph's node
should go away once the thread does an exclusive stop.

What I was not able to find is a daemon thread( IsBackground should be the
one , but I am skeptic unless my sample works)

regards
Govind



"Bill McCarthy" <Bill_McC@iprimus.com.au> wrote in message
news:398e2cd8@news.devx.com...
>
> "James Foxall" <jamesf@tigerpawsoftware.com> wrote in message
> news:398e1d28$1@news.devx.com...
> >
> > "Thomas Eyde" <thomas.eyde@eunet.no> wrote:
> > >This is a joke, right? Or..?
> > >
> > >I thought the AddressOf operator worked only on methods in a
..bas/modeule
> > >and not on those in a class. Or has that changed in VB.Net?
> >
> > You can use AddressOf in a class module now. Not only that, I was told
(in
> > a session at the PDC I thing) that you can now call functions without
your
> > own project using the address returned by AddressOf.
> >
>
> Yeh, but it makes me wonder how the instance of the class is handled by
the
> garbage collection, as I can't see the GC being able to know that an
> external dll has got a reference to a class's function. Hmm.. might have
to
> do some crash testing on that one.. <g>
>
>

[Michael \(michka\) Kaplan]

Is there a better way? Matt Curland's PushParamThunk is superior to the
methods you have given. :-)

--
MichKa

random junk of dubious value at the multilingual
http://www.trigeminal.com/ and a new book on
i18N in VB at http://www.trigeminal.com/michka.asp

"James Foxall" <jamesf@tigerpawsoftware.com> wrote in message
news:398e2ff8$1@news.devx.com...
>
> "Michael \(michka\) Kaplan" <former_mvp@spamfree.trigeminal.nospam.com>
wrote:
> >(and for people who want to do it in VB6, methods now exist for that sort
> of
> >thing <g>).
>
> Like keeping track of hooked user-controls in an array or linked list
within
> a Class module, or is there a better way? <Do tell! <g>>
>
> James Foxall

[Michael \(michka\) Kaplan]

I doubt that the second problem is reallysomething for them to fix.... any
more than they would ever handle the case where you delete a function but
not its callers.

--
MichKa

random junk of dubious value at the multilingual
http://www.trigeminal.com/ and a new book on
i18N in VB at http://www.trigeminal.com/michka.asp

"James Foxall" <jamesf@tigerpawsoftware.com> wrote in message
news:398e2f7a$1@news.devx.com...
>
> >Yeh, but it makes me wonder how the instance of the class is handled by
the
> garbage collection, as I can't see the GC being able to know that an
external
> dll has got a reference to a class's function. Hmm.. might have to do some
> crash testing on that one.. <g>
>
> Wow, Bill, that is a thought. I haven't got that far anyway. <g> I had a
> bizzare deal happen to me today. I placed a splitter control on a form,
but
> did not dock the control to an edge. For that matter, I don't believe it
> docked itself either. I then went into the code for the Win Form to dig
about
> a bit. When I tried to switch back to view the interface of the frm, I got
> an error about the splitter control having to be docked to an edge, and
that
> I couldn't view the form designer until I corrected this problem!!! As it
> turned out, I had no way to correct the problem (that I could come up with
> anyway) without viewing the Win Form in design view, since the code within
> the module is actually used to build the form at runtime. Circular problem
> and a New Project! Ouch!
>
> Another wierd thing, this one related to AddressOf. When you double-click
> a control you get the default event for the control (such as Click for a
> command button). .Net has been kind enough to add the code that hooks the
> control and uses AddressOf to point the hook to the new procdure. If you
> come back later and delete the procedure (not sure if it has to have code
> in it or not), Visual Basic gives you a compile error when you attempt to
> run the project, because it doesn't automatically delete the statement
that
> performs the hook! The statement with AddressOf is left holding an invalid
> function reference, so your project won't compile.
>
> There sure is a lot more to watch out for, even when doing simple things
> compared to Visual Basic 6. But there sure is a LOT more functiolity.
>
> James Foxall

[James Foxall]

"Michael \(michka\) Kaplan" <former_mvp@spamfree.trigeminal.nospam.com> wrote:
>Is there a better way? Matt Curland's PushParamThunk is superior to the
methods you have given. :-)

Sounds interesting. Where I could I learn more about that?

Thanks!

James Foxall

[James Foxall]

"Michael \(michka\) Kaplan" <former_mvp@spamfree.trigeminal.nospam.com> wrote:
>I doubt that the second problem is reallysomething for them to fix.... any
>more than they would ever handle the case where you delete a function but
>not its callers.

I'd have to argue this one. Millions of VB'ers are used to easily adding
an event (which doesn't seem so easy now), and just deleting it when they're
done. If VB generates the statement for you when you add the event handler,
it should remove the same statement when you delete the event handler. If
the behavior stays as is, it will confuse a LOT of people. Confused me at
first.

James Foxall