docs/guide/quick-start.md

In devOpifex/leprechaun: Create Simple 'Shiny' Applications as Packages

Quick Start

The "robustness" that leprechaun provides is thanks to R packages and the rigour they improse. Every leprechaun application is rooted in a package.

Setup

Therefore start from an R package. Create one whichever way you are more comfortable with; using the RStudio IDE, manually, or, as we do below, with the usethis package.

usethis::create_package("myapp")

This creates a package, if run from the RStudio IDE it should automatically open the project.

If you are not using RStudio create the package and move the root of the package then open your editor of choice, e.g.: below with VScode.

Rscript -e "usethis::create_package('myapp')"
code myapp

Once done, from the root of the package, scaffold a leprechaun application. This function accepts a single argument, ui to specify whether one wants a fluidPage or navbarPage for the UI, it defaults to the latter.

leprechaun::scaffold()

── Scaffolding leprechaun app ───────────────────────────────────────

── Creating lock file ──

✔ Creating .leprechaun

── Adding dependencies ──

✔ Adding 'shiny' to Imports in DESCRIPTION
✔ Adding 'bslib' to Imports in DESCRIPTION
✔ Adding 'htmltools' to Imports in DESCRIPTION


── Generating code ──

✔ Creating R/ui.R
✔ Creating R/assets.R
✔ Creating R/run.R
✔ Creating R/server.R
✔ Creating R/leprechaun-utils.R
✔ Creating R/zzz.R

✔ Creating inst/dev
✔ Creating inst/assets
✔ Creating inst/img

── Ignoring files ──

✔ Adding '^\\.leprechaun$' to '.Rbuildignore'

This creates a few files containing code necessary to run the application. To test it, document, and load the code, then call the run function that is now part of the package.

devtools::document()
devtools::load_all()
run()

That is it! Importantly leprechaun is not required to run the code it generates, only two dependencies were added: shiny, and bslib. The former is added because, by default, shiny runs on Bootstrap 3 which is 6 years out of date: using bslib to bump shiny to Bootstrap 4 is highly recommended!

Modules

Good practice has it that shiny code should be placed within "modules," they are easily reusable bundles of code, and are a great way to structure an application: compartmentalisation.

You can add modules with the function:

leprechaun::add_module(name = "counter")

The above creates a module_counter.R file containing the code for the module. The name is used to define the name of the file and functions of the module.

devOpifex/leprechaun documentation built on April 17, 2025, 4:31 a.m.