Left fold

This one's *not* be about programming... mostly. Ok, it is. It always is. This is an explanation on why I changed the name I had for this blog. The previous name was officially Run or Debug, but now I called Left Fold. Why would you do that, you ask? Well, the main story is because I hated the previous name but still I didn't have the courage (or the will) to change it. And truly, I didn't have a better name in mind... Until recently! I started to learn F# recently and as a guy who comes mostly from C# a lot of concepts were new to me, and some were not new, I just didn't know their name. It has been quite a journey, as anyone who has the same background as me would understand. I jumped from a general OOP language to a non-pure functional language. One of those concepts "learned" is called a left fold. I am aware it does exist in C# too, and it is all but new, but hear me out, I just never had thought about it this way . So, what the ...

Let's talk about accessor's accessibility introduced in C# 2.0. This is a tiny little feature that can make your life easier in a number of ways. But first, let's define what i am talking about. Normally, a property is composed this way: So, from the example above, we can see that a property has a backfield (called _myProperty) and is composed by a getter and a setter . The getter is called whenever you get the value of that property. The setter is called when you set it's value. If we look carefully, we notice that the getter returns the value of the backfield, and the setter sets it's value, respectively. If we think about it, a property is nothing more than a wrapper around a private field. This way we can control all the access to that field's value. C#'s properties are nothing more than sintactic sugar for the following structure: This is an " old school property ". In languages where you don't really have the concept of prop...

In C# 2 there was a new addition in the functionality called static classes and members . When i say "members", i am referring to methods, properties, events and so on. I have a strong opinion about this modifier which i will share with you along the article, but let's start by looking at what "static" means. Take this code as example: Above we can see that we define two properties and one is static. In the main method we then create an instance of Person and set the normal property ( Name ). Now notice the Person.NumberOfBrains  assignment. This is the static property we created in the class. Notice that the access is made at class level , instead of instance level.  This means that there will only be one NumberOfBrains  value throughout all Person instances, but there will be a Name  value per each instance  of Person . Of course, the example is not the best, but you get the idea. Static applies when all  instances share the same value. There are so...

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...

Today, let's look at a simple trick with strings in C#. It may be too obvious and repeated around the internet, but nevertheless i want to give my 2 cents on the subject. So, let's start! Imagine you have a list of any type and now you will need this values separated by a comma in order to be processed in some stored procedure. The desired output for a list of  {1,2,3,4} is a string like this "1,2,3,4" . How will you solve this problem? I've seen and done multiple approaches. Let's order the possible solutions (in my mind) from the most complex to the simpler. First, we can do: Notice how complex this can be, and how fast it can become messy. When replicated across an entire project (imagine the nightmare of having this replicated in your Data Access Layer whenever a stored procedure needs this input), this can be a pain. Of course, you could extract the behavior and create an extension method for it, but as we will see, it is not necessary. Our second...

Introduction My name is Mário Constantino, i'm Portuguese and i love what i do. I work as a junior developer at a small company for 2 years-ish now. This is where i started my career, so i'm still young and have the enthusiasm that comes with the age :) Our primary area is the development of ERP software in .NET technologies interacting with SQL. This gives me a little experience, but i'm far from an expert in the area, although i'm learning a lot each day. Blogging is a new experience for me, so you'll excuse me if i make some rookie mistakes. I've been on the internet since i can remember, but only on the consumer side, never on the producer. Well, for what it's worth, now i'm going to start to produce blog posts! But first, English is not my primary language, and some typos are in order. If you catch one, please tell me in a comment. I'm Portuguese, but i thought that by making the posts in English i would get a broader audience. Also, the...