Events: Demystifying Common Memory Leaks

Background If you've poked through my previous postings, you'll probably notice that I love using events when I program. If I can find a reason to use an event, I probably will. I think they're a great tool that can really help you with designing your architectures, but there are certainly some common problems people run into when they use events. The one I want to address today has to do with memory leaks. That's right. I said it. Memory leaks in your .NET application. Just because it's a managed language doesn't mean your code can't be leaking memory! And now that I've got your attention, let's see how events might be causing some leakage in your application. (There is source that you can download and run. Check the summary section at the end!) Instance-Scope Event Handlers One of the…

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Dependency Injected Singletons… What?

Background Previously I wrote a bit about singletons. I'm not afraid to say that I think singletons have a time and a place... Okay, I'm afraid to say it, but it's actually how I feel :) After learning more and more about inversion of control design patterns and programming by interfaces, I started to notice just how inflexible singletons are. When you consider using a singleton, you should be considering both the pros and cons without jumping right into it. Here's an example of my approach for mixing singletons, programming by interfaces, and a bit of inversion of control. The Setup I'm actually surprised you got this far. I'm sure you're probably just sticking around to see how messed up this could possibly be. I'm actually proud that this little pattern has worked out so well when I've used it,…

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Example: Getting Data Back From An EventHandler

Background I previously wrote about why I like to use events here and here. I figured it would be appropriate to illustrate a simple case where you can delegate decisions between functionally separate parts of code (say, between an application layer and a presentation layer). If you're well versed in C# and .NET, this might put you to sleep. If you have no idea what I'm talking about, hopefully this will help. By the end of this, hopefully you'll have a better idea for how you can use an EventHandler to pass data/state back through an invoked event... And don't forget to check out the code! The Scenario Let's assume we have a layered application, which is usually my go to. I might have three layers: one for data persistence, one for my business logic and one for interacting with…

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