How to destroy arrays

[Sarfraz Hooda]

Hi,

I have created an array of Objects in a collection. I was wondering is there
a way to destroy the array to free up the space in the memory ? or they are
automatically destroyed and garbagge collected by .Net framework?

Sarfraz

[Scott M.]

So then, would this make sense:

Sub Foo
Dim x as new FooFoo()
x.stuff()
'Done using x now, but don't want to wait for dispose to naturally run
x.dispose()

...some operation that will take time...
...some operation that will take time...
...some operation that will take time...
...some operation that will take time...

End Sub
Now, in this case, if there were clean up code in x's dispose method we
could control when it happens, rather than waiting for the GC to get around
to it?

-Scott

"Jon Skeet [C# MVP]" <sk***@pobox.co m> wrote in message
news:MP******** *************** *@msnews.micros oft.com...

Scott M. <s-***@nospam.nosp am> wrote:

First, you and Cor have been busy little bees on this....

:)

Second, my original reply (OR) and the "certain circumstances" that I was referring to have more to do with an object's Dispose() method firing and not so much about that object's eligibility for garbage collection.

Ah, right. Read on...

My understanding on this (and please correct me if I'm wrong) is that when an object falls out of scope, it will fire off its Dispose() method (if it has one).

No, that's not true. Dispose is only called if *something* calls it -
it's not automatic in most situations.

Now, C# has the "using" statement which *does* automatically call
Dispose at the end of the block, but that's basically just syntactic
sugar. Most finalizers call Dispose themselves, of course.

Then, when the object is actually about to be removed from memory
by the GC (which we can't say with any certainty if and when that happens), the object's Finalize method will fire.

Assuming it has one, and that GC.SuppressFina lize hasn't been called
for that object, yes.

My understanding has been that while an object may be eligible for garbage collection, if it hasn't fallen out of scope yet, then its Dispose method might not have fired yet. By setting the object to Nothing before the end of the procedure, you can get the Dispose method to fire sooner, rather than later. This can be very useful when the object is holding some expensive resource open or locked. So by getting Dispose to fire sooner, the
resources can be cleaned up sooner.

Is this not correct?

Nope - see above. It's certainly a good idea to call Dispose as soon as
you're able to (though no sooner, of course!) but that needs to be done
explicitly.

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too

[Jon Skeet [C# MVP]]

Scott M. <s-***@nospam.nosp am> wrote:

So then, would this make sense:

Sub Foo
Dim x as new FooFoo()
x.stuff()
'Done using x now, but don't want to wait for dispose to naturally run
x.dispose()

...some operation that will take time...
...some operation that will take time...
...some operation that will take time...
...some operation that will take time...

End Sub
Yup. (Assuming that FooFoo implements IDisposable, of course.)

If you don't call Dispose yourself, it could be a *very* long time
before resources are cleaned up - especially if the object is in
generation 2 (very unlikely in this case, but speaking about a more
general situation).
Now, in this case, if there were clean up code in x's dispose method we
could control when it happens, rather than waiting for the GC to get around
to it?

Yes. IDisposable should only be implemented for types either directly
containing unmanaged resources (handles etc) or for types which wrap
other types implementing IDisposable (eg StreamWriter, which wraps a
Stream).

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too

[Scott M.]

Ok Joh, thanks.

-Scott
"Jon Skeet [C# MVP]" <sk***@pobox.co m> wrote in message
news:MP******** *************** *@msnews.micros oft.com...

Scott M. <s-***@nospam.nosp am> wrote:

So then, would this make sense:

Sub Foo
Dim x as new FooFoo()
x.stuff()
'Done using x now, but don't want to wait for dispose to naturally run x.dispose()

...some operation that will take time...
...some operation that will take time...
...some operation that will take time...
...some operation that will take time...

End Sub

Yup. (Assuming that FooFoo implements IDisposable, of course.)

If you don't call Dispose yourself, it could be a *very* long time
before resources are cleaned up - especially if the object is in
generation 2 (very unlikely in this case, but speaking about a more
general situation).

Now, in this case, if there were clean up code in x's dispose method we
could control when it happens, rather than waiting for the GC to get around to it?

Yes. IDisposable should only be implemented for types either directly
containing unmanaged resources (handles etc) or for types which wrap
other types implementing IDisposable (eg StreamWriter, which wraps a
Stream).

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too

[Cor Ligthert]

Hi Scott,

Have a look at these pages, it has lot information about the GC and
describes it in my opinion very clear.

It as well describe dispose, however I saw in these newsgroups that the idea
about it is turning (also by Microsoft people), it is telling the old way
which even says that you have (when you follow the text) to dispose
everything by code that has a dispose method. Every control by instance has
it, however in my opinion is the dispose of that done by the component
class, which the control implements. About the dispose I have in general
probably the same idea as Jon now.

(In addition, please do not catch me on a word; in such a small message, not
everything is right)

However the pages are great, I got the link from Jay B. Harlow

http://msdn.microsoft.com/architectu...l/scalenet.asp

Cor