events & destructor

[lukasz]

When I attach an event handler (e.g. button.Click += new
EventHandler(Button_Clicked)) it's not necessary to remove the handler when
my class (or form) gets disposed or destroyed, is it? When my class gets out
of its scope and its time for GC-ing comes, it will be able to be destroyed
despite the "active" event handler?

[Scott Allen]

As soon as the Form becomes unreachable, that is, you have no
references to the Form object left, then the GC can clean up both the
form and the event handler (delegate) the Form references (assuming
the delegate in also unreachable). So no, you should not need to
remove the event handler.

HTH,

--
Scott
http://www.OdeToCode.com

On Sat, 4 Sep 2004 21:19:39 +0200, "lukasz" <bb****@op.pl> wrote:

When I attach an event handler (e.g. button.Click += new
EventHandler(Button_Clicked)) it's not necessary to remove the handler when
my class (or form) gets disposed or destroyed, is it? When my class gets out
of its scope and its time for GC-ing comes, it will be able to be destroyed
despite the "active" event handler?

[lukasz]

How about the situation with two objects, ObjUser and ObjService, ObjService
valid throughout the life span of the application and ObjUser being created
for a short time at certain moments. Now when I write in ObjUser's creator:

ObjService.OnChanged += new EventHandler(this.xxxx)

do I need to explicitly remove this handler? ObjService will still be in use
when ObjUser gets out of its scope.
Uzytkownik "Scott Allen" <bitmask@[nospam].fred.net> napisal w wiadomosci
news:4s********************************@4ax.com...

As soon as the Form becomes unreachable, that is, you have no
references to the Form object left, then the GC can clean up both the
form and the event handler (delegate) the Form references (assuming
the delegate in also unreachable). So no, you should not need to
remove the event handler.

HTH,

--
Scott
http://www.OdeToCode.com

On Sat, 4 Sep 2004 21:19:39 +0200, "lukasz" <bb****@op.pl> wrote:

When I attach an event handler (e.g. button.Click += new
EventHandler(Button_Clicked)) it's not necessary to remove the handler whenmy class (or form) gets disposed or destroyed, is it? When my class gets outof its scope and its time for GC-ing comes, it will be able to be destroyeddespite the "active" event handler?

[Scott Allen]

Hi lukasz:

In this case you might want to explicitly remove those handlers. If I
understand what you are saying - the Service will keep a reference to
the delegate and prevent it from being collected, and the delegate
holds a reference to to objUser which keeps objUser around.
This is an unfortunate scenario, you might want to google for "weak
reference delegate" as I believe some people have written code to
address the issue.

--
Scott
http://www.OdeToCode.com

On Sat, 4 Sep 2004 22:09:16 +0200, "lukasz" <bb****@op.pl> wrote:

How about the situation with two objects, ObjUser and ObjService, ObjService
valid throughout the life span of the application and ObjUser being created
for a short time at certain moments. Now when I write in ObjUser's creator:

ObjService.OnChanged += new EventHandler(this.xxxx)

do I need to explicitly remove this handler? ObjService will still be in use
when ObjUser gets out of its scope.
Uzytkownik "Scott Allen" <bitmask@[nospam].fred.net> napisal w wiadomosci
news:4s********************************@4ax.com.. .

As soon as the Form becomes unreachable, that is, you have no
references to the Form object left, then the GC can clean up both the
form and the event handler (delegate) the Form references (assuming
the delegate in also unreachable). So no, you should not need to
remove the event handler.

HTH,

--
Scott
http://www.OdeToCode.com

On Sat, 4 Sep 2004 21:19:39 +0200, "lukasz" <bb****@op.pl> wrote:

>When I attach an event handler (e.g. button.Click += new
>EventHandler(Button_Clicked)) it's not necessary to remove the handlerwhen >my class (or form) gets disposed or destroyed, is it? When my class getsout >of its scope and its time for GC-ing comes, it will be able to bedestroyed >despite the "active" event handler?
>