Mastering Shiny

Chapter 20. Packages

If you are creating a large or long-term Shiny app, I highly recommend that you organize your app in the same way as an R package. This means that you:

• Put all R code in the R/ directory.

• Write a function that starts your app (i.e., that calls shinyApp() with your UI and server).

• Create a DESCRIPTION file in the root directory of your app.

This structure gets your toes into the water of package development. It’s a long way from a complete package, but it’s still useful because it activates new tools that make it easier to work with a larger app. The package structure will pay off further when we talk about testing in Chapter 21, because you get tools that make it easy to run the tests and to see what code is tested. In the long run, it also helps you document complex apps using roxygen2, although we won’t discuss that in this book.

It’s easy to think of packages as giant complicated things like Shiny, ggplot2, or dplyr. But packages can also be very simple. The core idea of a package is that it’s a set of conventions for organizing your code and related artifacts: if you follow those conventions, you get a bunch of tools for free. In this chapter, I’ll show you the most important conventions and then provide a few hints as to next steps.

As you start working with app-packages, you may find that you enjoy the process of package development and want to learn more. I’d suggest starting with R Packages to get the lay of the package development land, then ...