This is either a bad bug, or I'm not understanding
somthing. In my mind, this should NOT work:

------------------------------------------
Class ShouldntWork
Delegate Sub goHere()

Sub StartHere()
Dim DC as new DeadClass
Dim myDel as New goHere(AddressOf DeadClass.Here)
DC = Nothing
GC.Collect
myDel.Invoke
End Sub
End Class

Class DeadClass
Sub Here
MsgBox "How Did I Get Here?"
End Sub
End Class
--------------------------------------

I'm assuming that since a delegate is really just a
pointer to a place in memory, that invoking it still sends
us there, but isn't this dangerous? Assume that that
location on the heap has been overwritten, who knows what
will happen, right?

Comments, Please!

Havent used delegates much, but

Just guessing, as you instantiate a delegate myDel, the removal of the
reference DC to the delegate has no effect.

OHM#

ZorpiedoMan wrote:
> This is either a bad bug, or I'm not understanding
> somthing. In my mind, this should NOT work:
>
> ------------------------------------------
> Class ShouldntWork
> Delegate Sub goHere()
>
> Sub StartHere()
> Dim DC as new DeadClass
> Dim myDel as New goHere(AddressOf DeadClass.Here)
> DC = Nothing
> GC.Collect
> myDel.Invoke
> End Sub
> End Class
>
> Class DeadClass
> Sub Here
> MsgBox "How Did I Get Here?"
> End Sub
> End Class
> --------------------------------------
>
> I'm assuming that since a delegate is really just a
> pointer to a place in memory, that invoking it still sends
> us there, but isn't this dangerous? Assume that that
> location on the heap has been overwritten, who knows what
> will happen, right?
>
> Comments, Please!

Regards - OHM# (E-Mail Removed)

That's correct, but the place in memory that is being
called should no longer be available... that's what has me
worried.

I think it's surely because of the Garbage Collector running in the back.

Use gc.collect after set to nothing and try again.
<(E-Mail Removed)> schrieb im Newsbeitrag
news:04f001c3c024$2e4e1290$(E-Mail Removed)...
> That's correct, but the place in memory that is being
> called should no longer be available... that's what has me
> worried.
>

After using GC.Collect execute GC.WaitForPendinfFinalizers that will wait
until GC is done collecting..


"ZorpiedoMan" <(E-Mail Removed)> wrote in message
news:1234301c3c01f$c2adb8f0$(E-Mail Removed)...
> This is either a bad bug, or I'm not understanding
> somthing. In my mind, this should NOT work:
>
> ------------------------------------------
> Class ShouldntWork
> Delegate Sub goHere()
>
> Sub StartHere()
> Dim DC as new DeadClass
> Dim myDel as New goHere(AddressOf DeadClass.Here)
> DC = Nothing
> GC.Collect
> myDel.Invoke
> End Sub
> End Class
>
> Class DeadClass
> Sub Here
> MsgBox "How Did I Get Here?"
> End Sub
> End Class
> --------------------------------------
>
> I'm assuming that since a delegate is really just a
> pointer to a place in memory, that invoking it still sends
> us there, but isn't this dangerous? Assume that that
> location on the heap has been overwritten, who knows what
> will happen, right?
>
> Comments, Please!

"ZorpiedoMan" <(E-Mail Removed)> schrieb
> This is either a bad bug, or I'm not understanding
> somthing. In my mind, this should NOT work:
>
> ------------------------------------------
> Class ShouldntWork
> Delegate Sub goHere()
>
> Sub StartHere()
> Dim DC as new DeadClass
> Dim myDel as New goHere(AddressOf DeadClass.Here)
> DC = Nothing
> GC.Collect
> myDel.Invoke
> End Sub
> End Class
>
> Class DeadClass
> Sub Here
> MsgBox "How Did I Get Here?"
> End Sub
> End Class
> --------------------------------------
>
> I'm assuming that since a delegate is really just a
> pointer to a place in memory, that invoking it still sends
> us there, but isn't this dangerous? Assume that that
> location on the heap has been overwritten, who knows what
> will happen, right?
>
> Comments, Please!

I also think it should not work: "Here" is not a shared method, so it should
be "...addresof dc.here".

Apart from this, it _should_ work because the delegate still points to the
DC object => there is still a reference to the object => The object is not
collected.


--
Armin

http://www.plig.net/nnq/nquote.html
http://www.netmeister.org/news/learn2quote.html

Thanks, but that STILL does not answer the question as to
WHY any code executes at all??? The delegate is pointing
to UNUSED memory... there could be ANYTHING at that
point... serious potential crashing possibilities...

The memory space isn't completely unused just becuase you set it to nothing,
Which is why I recomended GC.WaitforpendingFinalizers because GC.Collete
runs in a different thread. it's sort of like deleting a file you delete it
but the data of the file is still on the drive..


<(E-Mail Removed)> wrote in message
news:058e01c3c02b$65141ed0$(E-Mail Removed)...
> Thanks, but that STILL does not answer the question as to
> WHY any code executes at all??? The delegate is pointing
> to UNUSED memory... there could be ANYTHING at that
> point... serious potential crashing possibilities...

Hi,

Yes, this is correct behaviour. The delegate stores a reference to both the
target and the method in the target for instance methods. This enables the
GC to move the object in memory, and still reference the same method.
See Delegate class in the framework documents for more info.




"ZorpiedoMan" <(E-Mail Removed)> wrote in message
news:1234301c3c01f$c2adb8f0$(E-Mail Removed)...
> This is either a bad bug, or I'm not understanding
> somthing. In my mind, this should NOT work:
>
> ------------------------------------------
> Class ShouldntWork
> Delegate Sub goHere()
>
> Sub StartHere()
> Dim DC as new DeadClass
> Dim myDel as New goHere(AddressOf DeadClass.Here)
> DC = Nothing
> GC.Collect
> myDel.Invoke
> End Sub
> End Class
>
> Class DeadClass
> Sub Here
> MsgBox "How Did I Get Here?"
> End Sub
> End Class
> --------------------------------------
>
> I'm assuming that since a delegate is really just a
> pointer to a place in memory, that invoking it still sends
> us there, but isn't this dangerous? Assume that that
> location on the heap has been overwritten, who knows what
> will happen, right?
>
> Comments, Please!

"Bill McCarthy" <(E-Mail Removed)> schrieb
>
> Yes, this is correct behaviour. The delegate stores a reference to
> both the target and the method in the target for instance methods.
> This enables the GC to move the object in memory, and still reference
> the same method. See Delegate class in the framework documents for
> more info.

That's what I said. Good to know I was right. :-)


--
Armin

http://www.plig.net/nnq/nquote.html
http://www.netmeister.org/news/learn2quote.html