Dependency Injection with Autofac – A Primer

Before Autofac... I've written before about IoC and dependency injection, but these are older posts and my perspective and experience with these topics has fortunately been growing. I think they're incredibly important when you're building complex systems, but the concepts can offer some benefits in all of your programming! When you get in the habit of practicing this kind of thing, you can get some pretty flexible code... for free. So a quick recap on what I mean by dependency injection here... I'm mostly focused on passing interfaces into constructors (and yes, I'm going to be using C# terminology as I do in most of my programming examples, but these concepts are generally the same in other languages). The benefits here: You can write implementations that don't depend on other implementations... Just an API. Not depending on an interface means…

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What Makes Good Code? – Should Every Class Have An Interface? Pt 2

Should Every Class Have an Interface? This is part two in the sub-series of "Should Every Class Have an Interface?", and part of the bigger "What Makes Good Code?" series. Other Peoples' Code So in the last post, we made sure we could get an interface for every class we made. Okay, well that's all fine and dandy (I say half sarcastically). But you and I are smart programmers, so we like to re-use other peoples' code in our own projects. But wait just a second! It looks like Joe Shmoe didn't use interfaces in his API that he created! We refuse to pollute our beautiful interface-rich code with his! What can we do about it? Wrap it. That's right! If we add a little bit of code we can get all the benefits as the example we walked through originally. It's…

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ProjectXyz: Enforcing Interfaces (Part 2)

Enforcing Interfaces This is my second installment of the series related to my small side project that I started. I mentioned in the first post that one of the things I wanted to try out with this project is coding by interfaces. There's an article over at CodeProject that I once read (I'm struggling to dig it up now, arrrrrghh) that really gave me a different perspective about using interfaces when I program. Ever since then I've been a changed man. Seriously. The main message behind the article was along the lines of: Have your classes implement your interface, and to be certain nobody is going to come by and muck around with your class's API, make sure they can't knowingly make an instance of the class. One of the easiest ways to do this (and bear with me here, I'm…

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Yield! Reconsidering APIs with Collections

Yield: A Little Background The yield keyword in C# is pretty cool. Being used within an iterator, yield lets a function return an item as well as control of execution to the caller and upon next iteration resume where it left off. Neat, right? MSDN documentation lists these limitations surrounding the use of the yield keyword: Unsafe blocks are not allowed. Parameters to the method, operator, or accessor cannot be ref or out. A yield return statement cannot be located anywhere inside a try-catch block. It can be located in a try block if the try block is followed by a finally block. A yield break statement may be located in a try block or a catch block but not a finally block. So what does this have to do with API specifications? A whole lot really, especially if you're dealing…

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Lambdas: An Example in Refactoring Code

Background: Lambdas and Why This Example is Important Based on your experience in C# or other programming languages, you may or may not be familiar with what a lambda is. If the word "Lambda" is new and scary to you, don't worry. Hopefully after reading this you'll have a better idea of how you can use them. My definition of a lambda expression is a function that you can define in local scope to pass as an argument provided it meets the delegate signature. It's probably pretty obvious to you that you can pass in object references and value types into all kinds of functions... But what about passing in a whole function as an argument? And what if you just want to declare a simple anonymous method right when you want to provide it to a function? Lambdas. So…

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API: Don’t Forget About The Non-Public API!

Background From an object oriented programming perspective, an application programming interface (API) is often referred to as the way other developers can interact with the public members of your class(es) and interface(s). Of course, API can be used to describe how one interacts with a web service (or other types of services), but for this discussion I'm limiting the scope to that of interfaces and classes. Limiting the definition of API to public members (or the equivalent of C#'s "public" in other languages) is omitting one huge part of what it encompasses. The purpose of this post is to clarify, in my opinion, why I think forgetting about the non-public API can lead to bad framework and API designs. API And The Audience I've written before about what I think makes a good API, and I had some comments on Code…

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