Left fold

One of the limitations that EF still has is the support for multiple databases. It simply does not support that option.out of the box. Allthough on UserVoice a lot of people have voted this feature, it still doesn’t exist. Credit where credit is due: this is not my original idea. I first downloaded the original script, used it and then i almost completely rewrote it to suit my needs and to improve certain aspects. I love Linq, so i used it a lot. The original and fantastic script can be found here The trick is making EF believe that those objects are in the database by using synonyms. I dont know if every EF-supported database allows synonyms or not, but this is possible in SQL Server (which i am using).   My script adds the ability to backup the edmx files first (which i find useful to prevent my model from being corrupted), replace the prefixes in the resulting model (which i had to do by hand with the other script) and finally reorder the navigation properties by al...

Let's get back to my series on the evolution of the C# language. Everybody is familiar with what a delegate is, right? We know that delegates are a big part of the events system in .Net. We register a method on that delegate ( called handler ) that is invoked when the delegate is invoked. In other words, a delegate simply points to a method. The advantage here is that, as the delegate wraps the method and is an object, we can simply pass it to a method as a parameter! Think about this: This is how we use a delegate in events, for instance. The class exposes the delegate and we register our method to listen it. When the delegate is called inside the class, all the registered methods will be called (because of this, we call it a Multicast Delegate ). This works well, because all you have to do is have a method with the required signature. In the example above, we needed to declare two methods just to make a Console.WriteLine. Isn't this too much? I think it's a bit to...

It's 3 am and i don't feel like sleeping. I've been helping a friend to work on his code and now i'm only partially tired. Well, why not continue with my series on the evolution of C#? Let's do it! So, this time i'm going to talk about nullable types . Everybody used them already, but back in .Net 1.0 they didn't exist. How did you represent a "no value present" value? Sure, string can have null, but null is different than empty, right? How do you represent an empty numeric type then? You check if it is bigger than 0? Well for some cases that's just how developers did it. Either that or create a constant value that represents a "no value". But, to me, that is not expressive enough . Basically, a nullable type is only a non-nullable type wrapped in the System.Nullable struct. This is a generic struct, so it makes use of the Generic features of C# 2.0. The struct is very simple, it contains only a HasValue and a Value proper...

For those of you interested, i found a very interesting list of features that were introduced in C# in  here . This is a very complete list that contains all the features, and i'm explaining them one by one in this post series. We've talked about  Generics  and  Iterators . Now it's time for some partial types . A partial type  is a type which definition is spread across one or more files. It doesn't have to be in multiple separated files, but can be. This is a very simple concept that can give us many benefits, let's see: If a type is partial, multiple developers can work on every part of it. This allows a more organized way of working and can lead to production improvement.  Winforms , for example, generates a partial class for the form so that the client can separately edit other parts it. This way, a part contains information about the design and the other contains the logic of the form. In fact, this is a very spread pattern across .Net. Ent...

It's been a while since i wrote the last post, but i did not forget my purpose of creating a series that shows the evolution of C#. Today i came here to talk about one of the most useful features of C#, even if you dont know you're using it. Let's talk about iterators ! What is an iterator? For those of you who didn't read about the iterator pattern somewhere in the internet or in the "Gang of Four" book, you can read a description  here . The iterator is a class/object/whatever which knows how to traverse a structure. So, if you have a list or collection of objects, an iterator would have the knowledge of how to traverse that collection and access each element that it contains. The iterator is a well known design pattern and is behind many of the wonderful that we have nowadays in .NET (Linq comes to mind). Why is it a feature? Truth be told, an iterator is a concept well known way before .NET even existed. Being an OO Design Pattern, the iterator has...

This is a well discussed matter throughout the internet. Everyone knows about generics, what they do and what they are used for, right? No. There is a variety of reasons why you wouldn't know about generics, and some of them are: You are new in the language You are not new in the language but never cared to learn it Simply because you never learned the basics about generics, it doesn't mean you've never used it. If you recognize this snippet, then you are already dealing with generics: So, what is the advantage of generics? Type safety Generics will allow you to catch the errors at compile time rather than runtime by enforcing the rules of type safety that make C# a statically typed language. This leads to increased productivity because you don't have to run the code to know that something is wrong. For example, if in the snippet above you tried to add a new item of type string, a compiler exception would be thrown. Typically, in C# 1.0, you would use an...

Today, let's talk about some history. Not that World War history, but the history and evolution of C# as a language. I would like to analyze the principal parts in one of the mainstream languages of mass production in today's software. Beware that most of what i am about to say is the fruit of much research, in part because when C# and the .NET became available i had not written a single line of code yet, so you can say that i am a newborn in this world. I'm inclined to change that, though, but every new discovery is done with much enthusiasm on my part, and i'm very proactive, which sometimes may upset my colleagues. One of the reasons i'm writing this article - and this blog all the same - is because i love to learn new things and share it with others. Enough talk, let's get to the point! The beginning of .Net The .NET platform brings a brand new and fresh way of programming your applications. Microsoft created the term "Managed Code" to refer t...