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📓 Console App Project Structure: How to Add More Code Files

In this lesson, we'll go over how to add more code files to our Shape Tracker project, and what namespaces we might add them to. We'll also learn that classes in the same namespace are in the same scope and therefore have access to each other without the need of a using directive.

Adding More Business Logic Files​

Let's say we want to expand our Shape Tracker project to add a class for Ellipse (which includes circles) and Rectangle (which includes squares). We might add functionality that will allow users to calculate the area of an ellipse or rectangle, but we're not concerned about those details right now. The big question is where should we add those classes? A straightforward rule to follow is to create separate files for each new class, such that our project structure looks like this:

ShapeTracker.Solution/
  ├── ShapeTracker/
  │     ├── Models/
  |     |     ├── Ellipse.cs
  |     |     ├── Rectangle.cs
  │     │     └── Triangle.cs
  │     ├── ShapeTracker.csproj
  │     └── Program.cs
  ├── .gitignore
  └── README.md

Since each of these classes are a part of our Shape Tracker models, we should also add each new class to the ShapeTracker.Models namespace:

Models/Ellipse.cs
namespace ShapeTracker.Models
{
  public class Ellipse
  {
    // Ellipse code here.
  }
}
Models/Rectangle.cs
namespace ShapeTracker.Models
{
  public class Rectangle
  {
    // Rectangle code here.
  }
}

As we can see in the above example, we can reuse existing namespaces in new files to add new classes to that namespace. All classes declared in the same namespace will 'know' about each other and be in the same scope. For example, this means we don't have to include a using directive for ShapeTracker.Models in order to use Triangle logic within our Rectangle class (even though there's not a good reason to do this anyways). Similarly, we don't need to include a brand new using directive in Program.cs to start using the Ellipse or Rectangle classes.

Another organization we could follow is adding all of our Shape Tracker models to one file. In this case, we could create a Shapes.cs and add the Triangle, Rectangle, and Ellipse classes within it. The project structure would look like this:

ShapeTracker.Solution/
  ├── ShapeTracker/
  │     ├── Models/
  │     │     └── Shapes.cs
  │     ├── ShapeTracker.csproj
  │     └── Program.cs
  ├── .gitignore
  └── README.md

Take note that the naming convention for files that contain multiple classes is to give the file a plural name, like Shapes.cs, and not Shape.cs.

And Shapes.cs would look like this (with some code omitted for brevity):

Models/Shapes.cs
namespace ShapeTracker.Models
{
  public class Rectangle
  {
    // Rectangle code here.
  }

  public class Ellipse
  {
    // Ellipse code here.
  }

  public class Triangle
  {
    // Triangle code here.
  }
}

In the example projects in the C# .NET course, we'll usually have one class per file. That's because it's more descriptive — as in, Ellipse class logic is found in Ellipse.cs — and individual files have less code in them. Because of these reasons, for the Shape Tracker app, I think it makes more sense to put each shape class within individual files. While there's no hard and fast rule for how you organize classes into files, you always want to make sure the choice you are making leads to source code that is descriptive and easy to navigate.

Adding More UI Logic Files​

For the console app projects we create in this course section, we'll likely be fine to put all UI logic in the Program class (separated into multiple methods) within Program.cs. However, if you end up creating a more complex UI logic in your console app, you may want to separate your UI into helper classes within multiple files to better keep your logic organized. A structure like that may look like this:

ShapeTracker.Solution/
  ├── ShapeTracker/
  │     ├── Models/
  |     |     ├── Ellipse.cs
  |     |     ├── Rectangle.cs
  │     │     └── Triangle.cs
  |     ├── UserInterfaceModels/
  |     |     └── Banners.cs
  │     ├── ShapeTracker.csproj
  │     └── Program.cs
  ├── .gitignore
  └── README.md

We've created a new folder called UserInterfaceModels/ within the ShapeTracker/ directory.

Notice that Program.cs is not inside the new UserInterfaceModels/ directory — that's because it's best practice to leave Program.cs in the root of the production/project directory since it is the entry point to our application.

Within UserInterfaceModels/ we have a made-up file called Banner.cs that will contain multiple classes within it, each of which has a static property that stores different banners:

UserInterfaceModels/Banners.cs
namespace ShapeTracker.UserInterfaceModels
{
  class WelcomeBanner
  {
    public static string Welcome { get; } = @"
  #####                                #######                                           
 #     # #    #   ##   #####  ######      #    #####    ##    ####  #    # ###### #####  
 #       #    #  #  #  #    # #           #    #    #  #  #  #    # #   #  #      #    # 
  #####  ###### #    # #    # #####       #    #    # #    # #      ####   #####  #    # 
       # #    # ###### #####  #           #    #####  ###### #      #  #   #      #####  
 #     # #    # #    # #      #           #    #   #  #    # #    # #   #  #      #   #  
  #####  #    # #    # #      ######      #    #    # #    #  ####  #    # ###### #    # 
                                                                                         ";
  }

  class GoodbyeBanner
  {
    // GoodbyeBanner code here.
  }

  class SubMenuBanner
  {
    // SubMenuBanner code here.
  }
}

First note that we're using a new namespace: ShapeTracker.UserInterfaceModels. That means if we want to use any class within the Banners.cs file in Program.cs, we'll need to add a new using directive: using ShapeTracker.UserInterfaceModels;.

Why not add the classes within Banner.cs to the namespace ShapeTracker, which contains the Program class and our project's entry point? Well, it would actually be fine to use the ShapeTracker namespace in Banner.cs.

In this example of growing our application's source code, we've opted to use three namespaces because it creates a clearer separation of source code:

  • ShapeTracker.Models for our business logic (everything in the Models/ directory).
  • ShapeTracker for our program's entry point in Program.cs.
  • ShapeTracker.UserInterfaceModels for our additional UI logic models (everything in the UserInterfaceModels/ directory).

However, you might prefer to keep the namespaces simple, and just go for two: one for the UI logic and the other for business logic. This organizational decision is yours. The baseline requirement is that you organize your code into namespaces so that your code is scalable.

Finally, note that we are not including the public access modifier on the WelcomeBanner, GoodbyeBanner, and SubMenuBanner classes. That means each of these classes will default to the access modifier of internal, which means that these classes are available publicly within this assembly, but not outside of the assembly. Why does this matter? The short answer is that we won't be testing our user interface logic, so this code only needs to be accessible within the ShapeTracker folder. The long answer is that ShapeTracker is one assembly, and when we write tests, we'll be creating a separate assembly; so any Shape Tracker code that we want accessible to our testing folder will need to have the public access modifier. We'll revisit this topic when we start writing tests.

Verbatim String Literals​

Before we move on, check out the above code snippet for Banner.cs again. Take note of the @ symbol in front of the string that contains the Welcome banner.

The @ symbol defines a verbatim string literal, which prints the string as-is, without changing formatting or evaluating any escape sequences. An example escape sequence is when we include \n within a string to momentarily escape the string, create a new line, and then go back to evaluating the string. Here's an example using the dotnet-script REPL:

> Console.WriteLine("Hello\nWorld");
Hello
World
> Console.WriteLine(@"Hello\nWorld");
Hello\nWorld

Ascii Banners​

Ascii text banners are a very cool way to decorate your console apps and create distinct sections within your UI. There's a lot of ascii text generators out there. Here's one you can use in the projects you create.

Summary​

Organizing code in C# is much the same as it is in JavaScript: we want to separate code by concern and use descriptive names. The big difference between the two languages is that C# has namespaces that we can use to further group code, beyond classes, files, and directories.

For namespaces, keep in mind two things:

  • We can reuse the same namespace across multiple files.
  • When classes are in the same namespace, they are in the same scope and automatically have access to each other.