Expression API Cookbook

This blog post is a strange one in a lot of ways, it is more of me pointing out a set of recipes and linking through to a related article. So  what are the recipes, and what will it show you, the reader how to do?

Well I am going to start with a wee story first (don’t worry the point is one  its way). A while back I got this email out the blue from this guy in the states  who was creating a MVVM framework for Windows 8, and I have kept in contact with  this dude (and he really is a dude, if I can convince him to upload an image,  you will see what I mean) and we got talking about his IOC container within his  MVVM framework, which is like MEF for Windows 8.

Looking through Ian’s code, it was immediately obvious to me, than Ian really  (and I do mean really) knew how to use the Expression API within .NET. This namespace has always  intrigued me, so I talked to Ian about the merits of writing a joint  kind of article, where we would effectively come up with some scenarios to solve  using the Expression API.

Ian said he would be more than happy to write the code  to any scenarios I could come up with, if I was happy to do the article writing  side of things. This seemed a very fair way to do it, so we have done just that.

Now you may be asking what is so cool about the Expression API, well one  thing I quite like is that you can literally write entire programs in it, and  another thing that you see time and time again, is creating compiled lambda  expressions that have been built up on the fly, which compile down to a  delegate, so provide uber fast performance when compared to reflection. That is  why the Expresson API can be useful (at least we feel that way).

That is essentially what the associated article is all about, we have a bunch of  scenarios that I came up with (which I hope are good ones) which Ian has coded  up. The examples range from simple property get/set through to some rather  complex examples where we show you how to do things like how to create  If-Then-Else Expressions and compute a HashCode for an object based of its  property values.

Here is a list of the scenarios we will be covering

  • Change tracker
  • Convert
  • Generic object HashCode computation
  • If-Then-Else
  • Property get/set
  • Dynamic where

Want to know more please read the full article over here


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