Designing great frameworks training: Member Types

re: Designing great frameworks training: Member Types

raul igrisan — Mon, 07 Feb 2005 08:22:00 GMT

Brad,
the synchronization in the singleton example you have linked to for slide 30 seems broken to me. each lazy initialization will wait on a different mutex.

thanks,
raul

re: Designing great frameworks training: Member Types

Brad Abrams[MSFT] — Mon, 07 Feb 2005 14:24:00 GMT

Here is the example that Rual is referring to (I believe)
public sealed class DBNull {
private DBNull() {}
public static readonly DBNull Value = new DBNull();
// instance Methods...
}

The way this works is that the first time the DBNull class is accessed, the JIT runs the type constructor for DBNull which allocates the instance of DBNull… Each time after that the cached DBNull is returned. Notice that JIT is responsible for ensuring that only one thread causes the DBNull’s type constructor to be run.

Does that help?

re: Designing great frameworks training: Member Types

raul igrisan — Mon, 07 Feb 2005 14:56:00 GMT

nope. the one I'm refferin is the the Gang of 4 's singleton http://www.dofactory.com/Patterns/PatternSingleton.aspx

<quote>
// Methods
public static LoadBalancer GetLoadBalancer()
{
// Support multithreaded applications through
// "Double checked locking" pattern which avoids
// locking every time the method is invoked
if( balancer == null )
{
// Only one thread can obtain a mutex
Mutex mutex = new Mutex();
mutex.WaitOne();

if( balancer == null )
balancer = new LoadBalancer();

mutex.Close();
}
return balancer;
}
</quote>

The last example you have given, the DBNull seems perfectly fine to me (thow the initialisation is not so lazy :)

Brad Abrams on Class Members (Summary)

John Wood's Blog — Tue, 08 Feb 2005 21:14:00 GMT

Brad Abrams on Class Members (Summary)

Designing Great Frameworks - Member Type Coding Conventions: Properties Methods Events Constructors Indexers

David Hayden - Sarasota Web Design Development - F — Wed, 09 Feb 2005 04:40:00 GMT

The Designing .NET Class Libraries: Member Types chat is today! (Wednesday, February 09, 2005 at 1:00 p.m. Pacific Time)

frankred's WebLog — Wed, 09 Feb 2005 22:00:00 GMT

re: Designing great frameworks training: Member Types

Vince Blasberg — Thu, 10 Feb 2005 06:39:00 GMT

Great information. One more better would be a WMA version for the commute. It's also not easy enough to find this information.

re: Designing great frameworks training: Member Types

Neil Cowburn — Thu, 10 Feb 2005 09:43:00 GMT

One request I have it is that these sessions are made as a downloadable package containing the ppt, wmv & transcript. That would be *invaluable*

re: Designing great frameworks training: Member Types

Brad Abrams[MSFT] — Thu, 10 Feb 2005 13:39:00 GMT

Thanks for the feedback Vince, Neil... I am working with the MSDN guys to see what I can do.

Video - Where did it go?

Chad Yost — Fri, 11 Feb 2005 19:37:00 GMT

Anyone know why the video is no longer showing up. I still hear it, but, since the redid the site on MSDN, there is no video. I like watching who is talking.

Designing great frameworks training: Designing Inherence hierarchies

Brad Abrams — Mon, 14 Feb 2005 22:08:00 GMT

re: Designing great frameworks training: Member Types

RGab — Tue, 01 Mar 2005 14:28:00 GMT

Hey Brad,

awesome training series, was fun listening you spreading knowledge :)

You are recommending using 'static readonly' fields instead of constants and only use constants when we are 101% sure that the literal won't change.

When using 'static readonly' though, FxCop recommends:

Resolution : "Field 'foo' is declared as 'static readonly'
but is initialized with a constant value '-1'. Mark
this field as 'const' instead."

Maybe it would be cool if FxCop pointed out the caveats of using const (compiler inlining the literal, versioning problems).

RGab