Comments on: IDisposable, Done Right

By: Jonathan C Dickinson

Jonathan C Dickinson — Tue, 22 Jan 2013 08:50:00 +0000

Did you read the comment?

Firstly, if your library is being consumed by a 3rd party you can’t guarantee that your best practices are being adhered to. There are bad programmers out there.
If your library is not being consumed by a 3rd party you can’t guarantee that your best practices are being adhered to, especially in threaded situations. Good programmers make mistakes.Throwing an ObjectDisposedException is better than double-disposing in absolutely every situation. Rolled back that transaction twice? “Yeah, but the controlling thread was in charge of disposing that object.” Try telling that to a customer who just lost millions to a bug that is easily avoided by simply not using a `bool`. At the very least it’s a lot more explanatory than a FileNotFoundException in a bug report.I don’t put hypothetical walls up around myself, I put up real barriers – and you are irresponsible if you don’t because there is a massive difference between what you should do and what could happen.

By: kamranayub

kamranayub — Thu, 27 Dec 2012 17:34:00 +0000

This is important, and this is a great tip! When I pulled down the latest ActionMailer.Net library from Nuget, I started getting StackOverflowExceptions. Turns out, they didn’t implement IDisposable correctly. I created a pull-request that fixes the issue, but in retrospect, I still missed some tips brought up in this article.

Thanks for sharing.

By: Shmueli Englard

Shmueli Englard — Wed, 26 Dec 2012 20:38:00 +0000

What do you think of http://dave-black.blogspot.com/2011/03/how-do-you-properly-implement.html? I’ve been using it as my template

By: Mark Lindell

Mark Lindell — Wed, 05 Dec 2012 16:49:00 +0000

That’s awesome… hey, wait a minute…

By: MasaSam

MasaSam — Tue, 04 Dec 2012 18:40:00 +0000

Good article. Only thing I’ve noticed to other dispose advice articles I have read is that the sample implementation here sets the private _disposed field to true when disposing has done. Some other articles advices to set, and what I usually do, to set the field true right after it is checked in the beginning of protected Dispose method to prevent entering the disposing lines twice.

By: RaptorXP

RaptorXP — Tue, 04 Dec 2012 15:02:00 +0000

Hmm yeah, I agree with previous comments. The suggestion in this post is only valid when you want to dispose of unmanaged resources. I can tell you that in 6 years working with .NET, I *NEVER* had to deal with unmanaged resources from .NET.

It is actually harmful to follow this recommendation if you don’t have unmanaged resources because implementing a finalizer in a class automatically promotes the object to Gen 2, and you’ll end up with poor GC performance.

By: Chris Patterson

Chris Patterson — Tue, 04 Dec 2012 14:26:00 +0000

If you are using any third-party library (including most of the .NET runtime, such as WCF and others) there no way you can achieve this “catch-free” system. If there is nothing the calling method can do about the exception (other than explode in a spectacular fashion) – why bother throwing the exception. Sometimes, RPC calls and the like just don’t end in a happy place, and that’s often just fine. Not to mention that so many people call Dispose in a catch block or finally block, without a try/catch around it, which can lead to entire application crashes.

Which sucks at 2am in a production 24×7 system. Plan for failure, and deal with it in the code so you can sleep at night.

By: Chris Patterson

Chris Patterson — Tue, 04 Dec 2012 14:22:00 +0000

If multiple threads are sharing a disposable resource, a parent or other thread should be responsible for disposing of it once the consuming threads have exited. Otherwise, a thread could dispose of something that another thread might still be using.

By: Chris Patterson

Chris Patterson — Tue, 04 Dec 2012 14:18:00 +0000

Both classes have their own private _disposed, so no problem there.

By: fflams

fflams — Tue, 04 Dec 2012 11:03:00 +0000

This is a good article for beginner developpers, however you should check your example.
When explaining how a derived class should override the Dispose(bool) method, you have it set the _disposed falg to true before calling the base.Dispose, that will result in the base class not doing its dispose job and simply setting object references to null….