Disposing objects

[Jerry Spence1]

I'm rather confused as to whether something should be disposed of, or not.
What is the general rule? How can you be sure of doing the right thing? I've
heard about disposing unmanaged resources but what is an unmanaged resource?

Does everything need disposing?

I've been using Webrequest, Webresponse, Streamreaders etc. How can I be
sure of what needs disposing?

Do these get automatically get disposed of at the end of the procedure that
declares them?

Is there any way to check my program to see if I have something that needs
disposing and is still using resources?

-Jerry

[Michel Posseth [MCP]]

Re: Disposing objects

Every object that implements an idisposable interface should be disposed of
i recomend you to write these objects in a using en using bloock

like this

Using Foo as new Foo.Lib

'''do your stuff

End using 'the end using will take care of disposing so no need to call it

also note that a declared variabel in a using block gets a block scope

Using Foo as new Foo.Lib
Dim Bla As string 'only accessible in the using block
'''do your stuff

End using



A unmanagaed resource is a resource that is not native to .Net but started
through interop , PInvoke etc etc
for instance API calls or COM objects

Object pointers that go out of scope will eventually be cleaned by the GC
however how and when this happens is a mystery that only the GC knows :-)

hth

Michel Posseth [MCP]

http://www.vbdotnetcoder.com

"Jerry Spence1" <123@dfgh.comsc hreef in bericht
news:p9adnXVn-LFgiXrVnZ2dnUVZ 8vqdnZ2d@posted .plusnet...

I'm rather confused as to whether something should be disposed of, or not.
What is the general rule? How can you be sure of doing the right thing?
I've heard about disposing unmanaged resources but what is an unmanaged
resource?
>
Does everything need disposing?
>
I've been using Webrequest, Webresponse, Streamreaders etc. How can I be
sure of what needs disposing?
>
Do these get automatically get disposed of at the end of the procedure
that declares them?
>
Is there any way to check my program to see if I have something that needs
disposing and is still using resources?
>
-Jerry
>

[Cor Ligthert[MVP]]

Re: Disposing objects

Michel,

Can you show me your latest program where you use the dispose method on
Label?

Cor

"Michel Posseth [MCP]" <MSDN@posseth.c omschreef in bericht
news:uDhDJMfJJH A.468@TK2MSFTNG P06.phx.gbl...

Every object that implements an idisposable interface should be disposed
of
i recomend you to write these objects in a using en using bloock
>
like this
>
Using Foo as new Foo.Lib
>
'''do your stuff
>
End using 'the end using will take care of disposing so no need to call
it
>
also note that a declared variabel in a using block gets a block scope
>
Using Foo as new Foo.Lib
Dim Bla As string 'only accessible in the using block
'''do your stuff
>
End using
>
>
>
A unmanagaed resource is a resource that is not native to .Net but started
through interop , PInvoke etc etc
for instance API calls or COM objects
>
Object pointers that go out of scope will eventually be cleaned by the GC
however how and when this happens is a mystery that only the GC knows :-)
>
hth
>
Michel Posseth [MCP]

http://www.vbdotnetcoder.com

>
>
>
>
>
"Jerry Spence1" <123@dfgh.comsc hreef in bericht
news:p9adnXVn-LFgiXrVnZ2dnUVZ 8vqdnZ2d@posted .plusnet...

>I'm rather confused as to whether something should be disposed of, or
>not. What is the general rule? How can you be sure of doing the right
>thing? I've heard about disposing unmanaged resources but what is an
>unmanaged resource?
>>
>Does everything need disposing?
>>
>I've been using Webrequest, Webresponse, Streamreaders etc. How can I be
>sure of what needs disposing?
>>
>Do these get automatically get disposed of at the end of the procedure
>that declares them?
>>
>Is there any way to check my program to see if I have something that
>needs disposing and is still using resources?
>>
>-Jerry
>>

>
>

[Michel Posseth [MCP]]

Re: Disposing objects

Aha ,, well you wanted more detailed info Cor ;-) ?

As we both know that calling Dispose in that case is not necesary as
Dispose is automatically called on all controls and components placed on
windows forms or user controls.

However in general the rule is

dispose everything that implements IDisposable


regards
Michel





"Cor Ligthert[MVP]" <notmyfirstname @planet.nlschre ef in bericht
news:7428BB1B-7722-4BCD-A3BE-2CBF453FE12B@mi crosoft.com...

Michel,
>
Can you show me your latest program where you use the dispose method on
Label?
>
Cor
>
"Michel Posseth [MCP]" <MSDN@posseth.c omschreef in bericht
news:uDhDJMfJJH A.468@TK2MSFTNG P06.phx.gbl...

>Every object that implements an idisposable interface should be disposed
>of
>i recomend you to write these objects in a using en using bloock
>>
>like this
>>
>Using Foo as new Foo.Lib
>>
>'''do your stuff
>>
>End using 'the end using will take care of disposing so no need to call
>it
>>
>also note that a declared variabel in a using block gets a block scope
>>
>Using Foo as new Foo.Lib
>Dim Bla As string 'only accessible in the using block
>'''do your stuff
>>
>End using
>>
>>
>>
>A unmanagaed resource is a resource that is not native to .Net but
>started through interop , PInvoke etc etc
>for instance API calls or COM objects
>>
>Object pointers that go out of scope will eventually be cleaned by the GC
>however how and when this happens is a mystery that only the GC knows
>:-)
>>
>hth
>>
>Michel Posseth [MCP]
>http://www.vbdotnetcoder.com
>>
>>
>>
>>
>>
>"Jerry Spence1" <123@dfgh.comsc hreef in bericht
>news:p9adnXV n-LFgiXrVnZ2dnUVZ 8vqdnZ2d@posted .plusnet...

>>I'm rather confused as to whether something should be disposed of, or
>>not. What is the general rule? How can you be sure of doing the right
>>thing? I've heard about disposing unmanaged resources but what is an
>>unmanaged resource?
>>>
>>Does everything need disposing?
>>>
>>I've been using Webrequest, Webresponse, Streamreaders etc. How can I be
>>sure of what needs disposing?
>>>
>>Do these get automatically get disposed of at the end of the procedure
>>that declares them?
>>>
>>Is there any way to check my program to see if I have something that
>>needs disposing and is still using resources?
>>>
>>-Jerry
>>>

>>
>>

>

[Cor Ligthert[MVP]]

Re: Disposing objects

Michel,

However in general the rule is
dispose everything that implements IDisposable
>

Who has given this general rule?
Or is it "yours" general rule, I don't that it is right to give things on
this board without telling that it is your general rule.

That the using has the dispose implemented is obvious, it is easier to
implement that, then spend time to find out if it should be there.

Cor

[=?ISO-8859-1?Q?G=F6ran_Andersson?=]

Re: Disposing objects

Jerry Spence1 wrote:

I'm rather confused as to whether something should be disposed of, or not.
What is the general rule? How can you be sure of doing the right thing? I've
heard about disposing unmanaged resources but what is an unmanaged resource?
>
Does everything need disposing?
>
I've been using Webrequest, Webresponse, Streamreaders etc. How can I be
sure of what needs disposing?
>
Do these get automatically get disposed of at the end of the procedure that
declares them?
>
Is there any way to check my program to see if I have something that needs
disposing and is still using resources?
>
-Jerry
>

There are two ways that you can choose which objects to dispose:

1. If it has a Dispose method, call it.

2. Read the documentation and possibly other sources to find out if the
object really needs disposing. If you find reliable information that
says that it's not needed, you can skip the Dispose call.

Some people will say that the first is the only correct way, some will
say that the second is. Both works, and you can choose the one that is
suitable for your current situation. If you don't have time to waddle
around in the docs, just call Dispose and be done with it.

--
Göran Andersson
_____

http://www.guffa.com

[Cor Ligthert[MVP]]

Re: Disposing objects

Michel,

Let me say it in another way:

A lot of people write "You have to dispose everything in a class that
Implements IDisposable.

Which classes implements standard IDisposable? That are classes as forms as
they are made with the designer, as you wrote already by the label,
everything that is in the component is automaticly disposed.

People who write "everything that implements Idisopsable" mostly mean (or
it is understood), "Everything that has a dispose method".

However a dispose method says nothing, you can create it in every class
where that is not already there and which can be inherited, but by that does
it not implement Idisposable.

The standard dispose method (as it is inherited from component) is often
overridden to release unmanaged resources as we see by instance in most
Sharepoint classes. For sure I simple use everywhere in Sharepoint the
dispose method as there classes are often not much more than Com wrappers
and they have used Dispose for the releasing of that. So I agree that in
Sharepoint it is good practise to use everywhere the Dispose method before
something goes out of scope.

However in AdoNet by instance there is nothing where the dispose method
"should" be used. I could find also until now nowhere the dispose method in
a Linq class.

I have always a proplem when people in a kind of autheritair way write (I
don't know if this is English word, but you understand it), that "dispose
should be used wherever a class implements Idisopsable". They are in my idea
just parroting, something I was not expecting from you.

jmo

:-)

Cor






"Michel Posseth [MCP]" <MSDN@posseth.c omschreef in bericht
news:%232X62hgJ JHA.5984@TK2MSF TNGP03.phx.gbl. ..

Aha ,, well you wanted more detailed info Cor ;-) ?
>
As we both know that calling Dispose in that case is not necesary as
Dispose is automatically called on all controls and components placed on
windows forms or user controls.
>
However in general the rule is
>
dispose everything that implements IDisposable
>
>
regards
Michel
>
>
>
>
>
"Cor Ligthert[MVP]" <notmyfirstname @planet.nlschre ef in bericht
news:7428BB1B-7722-4BCD-A3BE-2CBF453FE12B@mi crosoft.com...

>Michel,
>>
>Can you show me your latest program where you use the dispose method on
>Label?
>>
>Cor
>>
>"Michel Posseth [MCP]" <MSDN@posseth.c omschreef in bericht
>news:uDhDJMfJJ HA.468@TK2MSFTN GP06.phx.gbl...

>>Every object that implements an idisposable interface should be disposed
>>of
>>i recomend you to write these objects in a using en using bloock
>>>
>>like this
>>>
>>Using Foo as new Foo.Lib
>>>
>>'''do your stuff
>>>
>>End using 'the end using will take care of disposing so no need to call
>>it
>>>
>>also note that a declared variabel in a using block gets a block scope
>>>
>>Using Foo as new Foo.Lib
>>Dim Bla As string 'only accessible in the using block
>>'''do your stuff
>>>
>>End using
>>>
>>>
>>>
>>A unmanagaed resource is a resource that is not native to .Net but
>>started through interop , PInvoke etc etc
>>for instance API calls or COM objects
>>>
>>Object pointers that go out of scope will eventually be cleaned by the
>>GC however how and when this happens is a mystery that only the GC knows
>>:-)
>>>
>>hth
>>>
>>Michel Posseth [MCP]
>>http://www.vbdotnetcoder.com
>>>
>>>
>>>
>>>
>>>
>>"Jerry Spence1" <123@dfgh.comsc hreef in bericht
>>news:p9adnX Vn-LFgiXrVnZ2dnUVZ 8vqdnZ2d@posted .plusnet...
>>>I'm rather confused as to whether something should be disposed of, or
>>>not. What is the general rule? How can you be sure of doing the right
>>>thing? I've heard about disposing unmanaged resources but what is an
>>>unmanaged resource?
>>>>
>>>Does everything need disposing?
>>>>
>>>I've been using Webrequest, Webresponse, Streamreaders etc. How can I
>>>be sure of what needs disposing?
>>>>
>>>Do these get automatically get disposed of at the end of the procedure
>>>that declares them?
>>>>
>>>Is there any way to check my program to see if I have something that
>>>needs disposing and is still using resources?
>>>>
>>>-Jerry
>>>>
>>>
>>>

>>

>
>

[Michel Posseth]

Re: Disposing objects

IDisposable is a interface ( "Contract" ) , if the coder implemented
IDisposable you may asume that there is a reasson why he implemented this
"contract" in his code
so seeing from that light you "should" call the dispose method

http://msdn.microsoft.com/en-us/library/system.idisposable.dispose.aspx

page 201 of the VB.Net core reference

Because .Net objects don`t have real destructors , Well designed classes
should expose a method to let well behaved clients manually release any
resource such as files database connections and system objects as soon as
they do not need them any longer -- that is , just before setting the
reference to Nothing rather than waiting for for the subsequent garbage
collection .

Classes that want to provide this feature should implement IDisposable an
interface defined in the .Net Framework ............... ..........

page 202

..Net programming guidelines dictate that the dispose method of an object
should invoke the dispose method of all the inner objects that the current
object owns and that are hidden from the client code ......

so yes it is an official guideline it is not MY guideline and to make it
more interesting it is a guideline for all .Net languages


And yes call me the dispose police but if i see code to objects in my
company written that implement idisposable without using blocks i convert
them to using blocks as i believe it is sloppy programming and for
readability of the code
if a contract is signed you must conform to that contract if you like it or
not in real life and in the programming world .



Michel Posseth [MCP]

http://www.vbdotnetcoder.com

"Cor Ligthert[MVP]" <notmyfirstname @planet.nlschre ef in bericht
news:407A84E7-6629-4EF7-85E4-04E57F22EC6F@mi crosoft.com...

Michel,
>
Let me say it in another way:
>
A lot of people write "You have to dispose everything in a class that
Implements IDisposable.
>
Which classes implements standard IDisposable? That are classes as forms
as they are made with the designer, as you wrote already by the label,
everything that is in the component is automaticly disposed.
>
People who write "everything that implements Idisopsable" mostly mean (or
it is understood), "Everything that has a dispose method".
>
However a dispose method says nothing, you can create it in every class
where that is not already there and which can be inherited, but by that
does it not implement Idisposable.
>
The standard dispose method (as it is inherited from component) is often
overridden to release unmanaged resources as we see by instance in most
Sharepoint classes. For sure I simple use everywhere in Sharepoint the
dispose method as there classes are often not much more than Com wrappers
and they have used Dispose for the releasing of that. So I agree that in
Sharepoint it is good practise to use everywhere the Dispose method before
something goes out of scope.
>
However in AdoNet by instance there is nothing where the dispose method
"should" be used. I could find also until now nowhere the dispose method
in a Linq class.
>
I have always a proplem when people in a kind of autheritair way write (I
don't know if this is English word, but you understand it), that "dispose
should be used wherever a class implements Idisopsable". They are in my
idea just parroting, something I was not expecting from you.
>
jmo
>
:-)
>
Cor
>
>
>
>
>
>
"Michel Posseth [MCP]" <MSDN@posseth.c omschreef in bericht
news:%232X62hgJ JHA.5984@TK2MSF TNGP03.phx.gbl. ..

>Aha ,, well you wanted more detailed info Cor ;-) ?
>>
>As we both know that calling Dispose in that case is not necesary as
>Dispose is automatically called on all controls and components placed on
>windows forms or user controls.
>>
>However in general the rule is
>>
>dispose everything that implements IDisposable
>>
>>
>regards
>Michel
>>
>>
>>
>>
>>
>"Cor Ligthert[MVP]" <notmyfirstname @planet.nlschre ef in bericht
>news:7428BB1 B-7722-4BCD-A3BE-2CBF453FE12B@mi crosoft.com...

>>Michel,
>>>
>>Can you show me your latest program where you use the dispose method on
>>Label?
>>>
>>Cor
>>>
>>"Michel Posseth [MCP]" <MSDN@posseth.c omschreef in bericht
>>news:uDhDJMfJ JHA.468@TK2MSFT NGP06.phx.gbl.. .
>>>Every object that implements an idisposable interface should be
>>>disposed of
>>>i recomend you to write these objects in a using en using bloock
>>>>
>>>like this
>>>>
>>>Using Foo as new Foo.Lib
>>>>
>>>'''do your stuff
>>>>
>>>End using 'the end using will take care of disposing so no need to
>>>call it
>>>>
>>>also note that a declared variabel in a using block gets a block scope
>>>>
>>>Using Foo as new Foo.Lib
>>>Dim Bla As string 'only accessible in the using block
>>>'''do your stuff
>>>>
>>>End using
>>>>
>>>>
>>>>
>>>A unmanagaed resource is a resource that is not native to .Net but
>>>started through interop , PInvoke etc etc
>>>for instance API calls or COM objects
>>>>
>>>Object pointers that go out of scope will eventually be cleaned by the
>>>GC however how and when this happens is a mystery that only the GC
>>>knows :-)
>>>>
>>>hth
>>>>
>>>Michel Posseth [MCP]
>>>http://www.vbdotnetcoder.com
>>>>
>>>>
>>>>
>>>>
>>>>
>>>"Jerry Spence1" <123@dfgh.comsc hreef in bericht
>>>news:p9adnXV n-LFgiXrVnZ2dnUVZ 8vqdnZ2d@posted .plusnet...
>>>>I'm rather confused as to whether something should be disposed of, or
>>>>not. What is the general rule? How can you be sure of doing the right
>>>>thing? I've heard about disposing unmanaged resources but what is an
>>>>unmanaged resource?
>>>>>
>>>>Does everything need disposing?
>>>>>
>>>>I've been using Webrequest, Webresponse, Streamreaders etc. How can I
>>>>be sure of what needs disposing?
>>>>>
>>>>Do these get automatically get disposed of at the end of the procedure
>>>>that declares them?
>>>>>
>>>>Is there any way to check my program to see if I have something that
>>>>needs disposing and is still using resources?
>>>>>
>>>>-Jerry
>>>>>
>>>>
>>>>
>>>

>>
>>

>

[Michel Posseth]

Re: Disposing objects

The only thing i would like to add to this verry politicly correct answer of
Göran :-)


Failing to Dispose an object which implements IDisposable typically results
in the object going into the finalization queue (read Chapter 19 of Jeffrey
Richter's Applied Microsoft .NET Framework Programming for details). The
results of this is that an object's memory that might have otherwise been
freed in generation 01 be freed until a later generation collection. If
you're creating a lot of these objects, well, do the math."

So the worst thing that might happen is - that you should assume it could
cost you extra GC cycles if you don't ........


regards

And have a nice evening

Michel






"Göran Andersson" <guffa@guffa.co mschreef in bericht
news:eXrkBokJJH A.5984@TK2MSFTN GP03.phx.gbl...

Jerry Spence1 wrote:

>I'm rather confused as to whether something should be disposed of, or
>not. What is the general rule? How can you be sure of doing the right
>thing? I've heard about disposing unmanaged resources but what is an
>unmanaged resource?
>>
>Does everything need disposing?
>>
>I've been using Webrequest, Webresponse, Streamreaders etc. How can I be
>sure of what needs disposing?
>>
>Do these get automatically get disposed of at the end of the procedure
>that declares them?
>>
>Is there any way to check my program to see if I have something that
>needs disposing and is still using resources?
>>
>-Jerry

>
There are two ways that you can choose which objects to dispose:
>
1. If it has a Dispose method, call it.
>
2. Read the documentation and possibly other sources to find out if the
object really needs disposing. If you find reliable information that says
that it's not needed, you can skip the Dispose call.
>
Some people will say that the first is the only correct way, some will say
that the second is. Both works, and you can choose the one that is
suitable for your current situation. If you don't have time to waddle
around in the docs, just call Dispose and be done with it.
>
--
Göran Andersson
_____
http://www.guffa.com

[=?ISO-8859-1?Q?G=F6ran_Andersson?=]

Re: Disposing objects

Michel Posseth wrote:

The only thing i would like to add to this verry politicly correct
answer of Göran :-)
>
>
Failing to Dispose an object which implements IDisposable typically
results in the object going into the finalization queue (read Chapter 19
of Jeffrey Richter's Applied Microsoft .NET Framework Programming for
details). The results of this is that an object's memory that might have
otherwise been freed in generation 01 be freed until a later generation
collection. If you're creating a lot of these objects, well, do the math."
>
So the worst thing that might happen is - that you should assume it
could cost you extra GC cycles if you don't ........
>
>
regards
>
And have a nice evening
>
Michel
>

Good point. However, it only applies if the class actually has a finalizer.

So, if the class has a Dispose method and a finalizer, you should always
call the Dispose method.


--
Göran Andersson
_____

http://www.guffa.com

[Brian Gideon]

Re: Disposing objects

On Oct 4, 3:31 am, "Cor Ligthert[MVP]" <notmyfirstn... @planet.nl>
wrote:

Michel,
>
Can you show me your latest program where you use the dispose method on
Label?
>
Cor

Controls are disposed automatically so it would not be difficult to
satisfy that request. In fact, you could probably just pull up a few
of your own.

[Brian Gideon]

Re: Disposing objects

On Oct 4, 1:23 pm, "Cor Ligthert[MVP]" <notmyfirstn... @planet.nl>
wrote:

Michel,
>
Let me say it in another way:
>
A lot of people write "You have to dispose everything in a class that
Implements IDisposable.

I am in that camp.

>
Which classes implements standard IDisposable? That are classes as forms as
they are made with the designer, as you wrote already by the label,
everything that is in the component is automaticly disposed.
>
People who write "everything that implements Idisopsable"  mostly mean (or
it is understood), "Everything that has a dispose method".
>
However a dispose method says nothing, you can create it in every class
where that is not already there and which can be inherited, but by that does
it not implement Idisposable.

When I'm talking about calling Dispose I'm specifically referring to
classes that implement IDisposable. I'm not aware of any classes that
have a Dispose method without implementing IDisposable; at least in
the BCL.

>
The standard dispose method (as it is inherited from component) is often
overridden to release unmanaged resources as we see by instance in most
Sharepoint classes. For sure I simple use everywhere in Sharepoint the
dispose method as there classes are often not much more than Com wrappers
and they have used Dispose for the releasing of that. So I agree that in
Sharepoint it is good practise to use everywhere the Dispose method before
something goes out of scope.
>

Just to clarify, the standard Dispose method is not marked as virtual
so it actually cannot be overriden. However, the protected
Dispose(Boolean ) can be overriden.

However in AdoNet by instance there is nothing where the dispose method
"should" be used. I could find also until now nowhere the dispose method in
a Linq class.
>

Do you understand the consequences of not calling Dispose on say...a
SqlConnection instance?

I have always a proplem when people in a kind of  autheritair way write(I
don't know if this is English word, but you understand it), that "dispose
should be used wherever a class implements Idisopsable". They are in my idea
just parroting, something I was not expecting from you.
>

I happen to put a lot of stock in the MSDN documentation myself.

[Brian Gideon]

Re: Disposing objects

On Oct 4, 12:52 pm, Göran Andersson <gu...@guffa.co mwrote:

Jerry Spence1 wrote:

I'm rather confused as to whether something should be disposed of, or not.
What is the general rule? How can you be sure of doing the right thing?I've
heard about disposing unmanaged resources but what is an unmanaged resource?

>

Does everything need disposing?

>

I've been using Webrequest, Webresponse, Streamreaders etc. How can I be
sure of what needs disposing?

>

Do these get automatically get disposed of at the end of the procedure that
declares them?

>

Is there any way to check my program to see if I have something that needs
disposing and is still using resources?

>

-Jerry

>
There are two ways that you can choose which objects to dispose:
>
1. If it has a Dispose method, call it.
>
2. Read the documentation and possibly other sources to find out if the
object really needs disposing. If you find reliable information that
says that it's not needed, you can skip the Dispose call.
>
Some people will say that the first is the only correct way, some will
say that the second is. Both works, and you can choose the one that is
suitable for your current situation. If you don't have time to waddle
around in the docs, just call Dispose and be done with it.
>

I like to sum it up this way. When in doubt call Dispose. That
usually leads me to preferring #1.

[Cor Ligthert[MVP]]

Re: Disposing objects

>Do you understand the consequences of not calling Dispose on say...a
>SqlConnectio n instance?

http://groups.google.com/group/microsoft.public.dotnet.framework.adonet/msg/7111c0671640ad38

Cor

[Brian Gideon]

Re: Disposing objects

On Oct 5, 10:59 pm, "Cor Ligthert[MVP]" <notmyfirstn... @planet.nl>
wrote:

Do you understand the consequences of not calling Dispose on say...a
SqlConnection instance?

>
http://groups.google.com/group/micro...framework.adon...
>
Cor

Yeah, Close and Dispose both close the connection. Everybody knows
that. So calling Close is the next best thing in lieu of calling
Dispose. That's great.

What other benefits do you miss out on by not calling Dispose? What
other unmanaged resources are left dangling until the GC runs the
finalizer? By analyzing with Reflector I can see that you'd only be
limited to keeping the object on the finalization queue...right now
anyway.

What would happen if Microsoft decided to tweak the implementation so
that Dispose did more things in a future version?

Now take a look at OleDbConnection using Reflector. Dispose really is
doing more than just closing the connection in that case. What about
a proprietary IDbConnection?

I'm currently working on a native .NET managed provider for a
proprietary database. I can tell you that Dispose is more aggressive
in releasing unmanaged resources than Close in my implementation.