Run an app with hot reload — dev

Watches a .R file for changes and automatically re-runs it when saved. The file is sourced directly in the current R session. When the app exits (user quits or it crashes), the file's modification time is checked and the app re-sources if the file changed.

Usage

dev_app(file, poll = 1)

Arguments

file: Path to an .R file that runs an rtui app.
poll: Polling interval in seconds for file change detection (used when waiting for changes after app exit). Default 1.

Value

Called for its side effect (runs the app in a loop). Returns NULL invisibly when interrupted.

Details

Workflow: edit your .R file in an editor, save, then quit the running app (e.g. press q) - it restarts automatically with your changes. If the app crashes, it waits for the next file save before restarting.

Press Ctrl+C when the app is not running (i.e. between restarts) to stop the watcher.

dev_app() is designed for rapid development iteration. It:

Sources and runs the given .R file
When the app exits, checks if the file was modified
If modified: re-sources immediately
If not modified: polls until the file changes, then re-sources
Continues until you press Ctrl+C between app runs

Because the file is sourced directly (not via a subprocess), the app gets full terminal control and all keyboard/mouse input works normally.

Examples

if (FALSE) { # \dontrun{
# In a terminal:
dev_app("my_app.R")

# Edit my_app.R in your editor, save, quit the app - it restarts
} # }