.NET Packages

As developers we write a lot of code. However, we don't want to reinvent the wheel, that is write code to do a basic task that is needed in many applications. For instance, it wouldn't make sense for each developer, on every project, to write code to output a variable to the console. This is a common task that we'd prefer another developer create and just share that code with us.

This is what packages are for. Just about every modern programming language has a way of taking a set of related code, grouping it together and making it available in a package. Not every language calls this packages, for instance the Ruby language calls them gems.

Built in packages

Many language and environments, C# and .NET included, bundle a set of code packages into their default installation. We often refer to these as core libraries or core packages. These are bits of code we can use without telling our projects to download external libraries or packages.

For instance, in .NET, we use Console.WriteLine to output to the console. This code is available to us in the System library. Once we tell a csharp file that we are using System we can now use all the code provided by System.

To add more features we need to reach for external libraries

Adding external library

Console.WriteLine is available to us from built in libraries/packages, but it outputs very plain text. What if we wanted to add some pizzazz to our output by coloring the text?

If we wanted ENTER to be in a different color below.

Console.WriteLine("Press ENTER to continue");

We can add an external library of code to our project. When the following command is ran inside our .NET project, we are telling .NET to find, download, and add to our project all the code for a library called Pastel

dotnet add package Pastel

How did we know there was such a library? For dotnet there is a central repository of packages called nuget. From this site we can search for existing code that solves a problem. nuget also gives us links to the project pages where we can find documentation. Following the project page for Pastel we see the code works like this:

Console.WriteLine($"Press {"ENTER".Pastel(Color.FromArgb(165, 229, 250))} to continue");

And this will output the word ENTER in color.

What are the downsides of external libraries?

The more external code we add to our project the more we are tying our code to something another has written. As our project moves forward, and as time progresses, perhaps that library will not grow to continue to meet our needs. We need to continually review our project's dependencies as we upgrade our code, tools, and even the language itself.

How to know when to bring in a package?

If a code need is small, maybe you need to process a string a certain way, reaching for a large library that has the feature you need, but also dozens (or hundreds) more might not be reasonable. Maybe you can write that code yourself and avoid a dependency on an external library. As a developer, or a team, we have to consider the tradeoffs of build versus buy (in this case for free, but with the costs we mentioned above)

Standing on the shoulders

The fact that whole communities of developers are writing code that allow us to, with simple commands, extend our applications and easily add features allows us to stand on the shoulder of giants. Even better that most of this code is available to us for free and often licensed that we can freely use it in our commercial applications. As we grow our developer skills we should be supporting these communities and eventually, hopefully, giving back by authoring our own code packages to share with others.