https://github.com/dgkf/callbackconnection

A connection target for R allowing arbitrary R code execution on stdout and stderr messages
https://github.com/dgkf/callbackconnection

Last synced: about 2 months ago
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A connection target for R allowing arbitrary R code execution on stdout and stderr messages

• Host: GitHub
• URL: https://github.com/dgkf/callbackconnection
• Owner: dgkf
• Created: 2018-11-09T19:24:51.000Z (over 6 years ago)
• Default Branch: master
• Last Pushed: 2018-11-09T22:41:30.000Z (over 6 years ago)
• Last Synced: 2025-02-05T03:49:30.975Z (4 months ago)
• Language: C
• Homepage:
• Size: 6.84 KB
• Stars: 1
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# callbackConnection

A new connection target for R allowing arbitrary R code execution on stdout and

stderr messages

# Example [app.R](/examples/app.R)

Changing the input of the `selectInput()` prints, emits a message or an error.

```r

# relevant snippet

output$out <- renderText({

  if (input$selection %in% "error something") {

    stop(input$selection) # cause an error

  } else if (input$selection %in% "message something") {

    message(input$selection)

  } else {

    print(input$selection)

  }

  input$selection

})

```







# Motivation

This was a proof of concept put together to alleviate my coworkers' difficulties

in accessing shiny app log files on a shared shiny server. I aimed to generalize

the problem to be able to handle arbitrary callbacks, though the primary goal

was to issue outputs to the JavaScript console in a browser using

`shinyjs::runjs()`.

For more details, please take a look at the example [app.R](/examples/app.R). 

# Known Issues

Within a shiny app, this callback is somewhat error prone and seems to cause

random crashes of the running app. It is by no means a polished product, and

hinges on some sloppy C code (my first attempt at writing C in about a

decade).