I was the one that advised that this might not be the correct list to
post to. I am relatively new to the list and although I am not exactly
sure of the scope of this list, though the e-mails I have seen so far
have been much more advanced in subject matter than what further
discussion off-list uncovered this thread to regard. So my perception
could be incorrect, which is why I qualified my suggestion when I made
it, perhaps too weakly. Probably I should just lurk for a while longer
to get a good feel for the list's content.
What I found to be the question was:
"Do distinct instances of a class hold references to the same member
variable data?"
In code:
public class Foo {
public string Bar = "unchanged";
}
public void Main() {
Foo foo1 = new Foo();
Foo foo2 = new Foo();
foo1.Bar = "new value";
if( foo1.Bar == foo2.Bar ) {
//Answer is Yes
}
else {
//Answer is No
}
}
The full conversation follows (ordered by time):
> I usually define something like (C#):
>
> private object _lock = new object();
>
> then, in the areas where concurrent access could be problematic:
>
> lock( _lock ) {
> //Do things that need to be protected from multi-threaded issues.
> }
>
> There are good resources on this subject on the web. What I have
> written is the simplest approach, there are many others that are
> often better depending on the situation. You should evaluate them
> in regards to your own.
>
> Erik
NEXT MESSAGE:
> Hi. Thanks for the reply. I'm not sure if it applies in my situation;
> here's an example:
>
> ----- 8< -----
> Dim MessageMI1 As New CommMessageMI1
> MessageMI1.Model = Me.hidModel.Value.ToString MessageMI1.Chassis =
> Me.hidChassis.Value.ToString
> ----- >8 -----
>
> CommMessageMI1 is derived from another class CommMessage
> ----- 8< -----
> Public Class CommMessage
> Public intUserID As Integer
> Public strModel As String
> Public strChassis As String
>
> Public Property Model() As String
> Get
> Return strModel
> End Get
> Set(ByVal value As String)
> strModel = value
> End Set
> End Property
> Public Property Chassis() As String
> Get
> Return strChassis
> End Get
> Set(ByVal value As String)
> strChassis = value
> End Set
> End Property
> End Class
> ----- >8 -----
>
> What I am worried about is if I set the Model and Chassis propreties
> of my instance 'MessageMI1', and another user creates an instance in
> another session, will the Model and Chassis properties be changed in
> all other instances?
>
> I hope that makes sense - bit new to OOP here.
> Ben
NEXT MESSAGE:
> I'm not hugely familiar with ASP, but here's what I think:
>
> If the second user is actually creating a new instance (and thus
> you really have distinct instances), then the values inside of
> them should be references to different locations in memory.
> Encapsulation should enforce this.
>
> The question I have is why you haven't just written up a test to
> find out? How could you test your understanding and discern which
> is the case (that both change or that they are separate)? It would
> take less time generally to test than try and get an answer from
> someone else and you'll end up learning about the technology in
> the process.
>
> As a meta-note. I am new to this list, but I don't believe that
> these sorts of basic questions are appropriate here. Instead, most
> of the posts I've seen are discussions of fundamental choices about
> the language and conceptual understanding of the same.
>
> Erik
(I was thinking, for example of the recent why isn't virtual a part of
the default method signature in DotNet)
Incidentally, the following e-mail uncovered a more basic and wide
ranging discussion point that could be of much more interest (load
issues), but ought to be (IMO) further drilled into for the purpose of
forming a question (though I hadn't said so yet). The relevant excerpt:
> I have written and tested this but have not managed to re-create
> the situation I experienced (heavy load) that drew my attention to
> the problem.
This subject may be of value here and I did in no way intend to
discourage Ben in finding an answer, but I was unaware of the wider
issue (or any related details) at the time I made my suggestion. Quite
possibly I could use some education regarding list content.
Sorry for any offense,
Erik
-----Original Message-----
From: Discussion of advanced .NET topics.
[mailto:[EMAIL PROTECTED] On Behalf Of Stoyan Damov
Sent: Tuesday, February 27, 2007 12:49 PM
To: ADVANCED-DOTNET@DISCUSS.DEVELOP.COM
Subject: Re: Creating thread-safe classes to use in an ASP.NET app
On 2/27/07, Ben Joyce <[EMAIL PROTECTED]> wrote:
> I've been advised off-list that this is not the place to ask this sort
> of questions, my apologies.
>
> Ben
Does this mean that:
a) multithreading is NOT an advanced topic or
b) mentioning ASP.NET along with multithreading makes your post
off-topic?
This is silly.
Cheers,
Stoyan
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