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Edit File: developing-with-clipr.html
<!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta charset="utf-8" /> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <meta name="generator" content="pandoc" /> <meta name="viewport" content="width=device-width, initial-scale=1"> <meta name="author" content="Matthew Lincoln" /> <meta name="date" content="2019-07-22" /> <title>Developing with clipr</title> <style type="text/css">body { background-color: #fff; margin: 1em auto; max-width: 700px; overflow: visible; padding-left: 2em; padding-right: 2em; font-family: "Open Sans", "Helvetica Neue", Helvetica, Arial, sans-serif; font-size: 14px; line-height: 1.35; } #header { text-align: center; } #TOC { clear: both; margin: 0 0 10px 10px; padding: 4px; width: 400px; border: 1px solid #CCCCCC; border-radius: 5px; background-color: #f6f6f6; font-size: 13px; line-height: 1.3; } #TOC .toctitle { font-weight: bold; font-size: 15px; margin-left: 5px; } #TOC ul { padding-left: 40px; margin-left: -1.5em; margin-top: 5px; margin-bottom: 5px; } #TOC ul ul { margin-left: -2em; } #TOC li { line-height: 16px; } table { margin: 1em auto; border-width: 1px; border-color: #DDDDDD; border-style: outset; border-collapse: collapse; } table th { border-width: 2px; padding: 5px; border-style: inset; } table td { border-width: 1px; border-style: inset; line-height: 18px; padding: 5px 5px; } table, table th, table td { border-left-style: none; border-right-style: none; } table thead, table tr.even { background-color: #f7f7f7; } p { margin: 0.5em 0; } blockquote { background-color: #f6f6f6; padding: 0.25em 0.75em; } hr { border-style: solid; border: none; border-top: 1px solid #777; margin: 28px 0; } dl { margin-left: 0; } dl dd { margin-bottom: 13px; margin-left: 13px; } dl dt { font-weight: bold; } ul { margin-top: 0; } ul li { list-style: circle outside; } ul ul { margin-bottom: 0; } pre, code { background-color: #f7f7f7; border-radius: 3px; color: #333; white-space: pre-wrap; } pre { border-radius: 3px; margin: 5px 0px 10px 0px; padding: 10px; } pre:not([class]) { background-color: #f7f7f7; } code { font-family: Consolas, Monaco, 'Courier New', monospace; font-size: 85%; } p > code, li > code { padding: 2px 0px; } div.figure { text-align: center; } img { background-color: #FFFFFF; padding: 2px; border: 1px solid #DDDDDD; border-radius: 3px; border: 1px solid #CCCCCC; margin: 0 5px; } h1 { margin-top: 0; font-size: 35px; line-height: 40px; } h2 { border-bottom: 4px solid #f7f7f7; padding-top: 10px; padding-bottom: 2px; font-size: 145%; } h3 { border-bottom: 2px solid #f7f7f7; padding-top: 10px; font-size: 120%; } h4 { border-bottom: 1px solid #f7f7f7; margin-left: 8px; font-size: 105%; } h5, h6 { border-bottom: 1px solid #ccc; font-size: 105%; } a { color: #0033dd; text-decoration: none; } a:hover { color: #6666ff; } a:visited { color: #800080; } a:visited:hover { color: #BB00BB; } a[href^="http:"] { text-decoration: underline; } a[href^="https:"] { text-decoration: underline; } code > span.kw { color: #555; font-weight: bold; } code > span.dt { color: #902000; } code > span.dv { color: #40a070; } code > span.bn { color: #d14; } code > span.fl { color: #d14; } code > span.ch { color: #d14; } code > span.st { color: #d14; } code > span.co { color: #888888; font-style: italic; } code > span.ot { color: #007020; } code > span.al { color: #ff0000; font-weight: bold; } code > span.fu { color: #900; font-weight: bold; } code > span.er { color: #a61717; background-color: #e3d2d2; } </style> </head> <body> <h1 class="title toc-ignore">Developing with clipr</h1> <h4 class="author">Matthew Lincoln</h4> <h4 class="date">2019-07-22</h4> <div id="calling-clipr-safely" class="section level2"> <h2>Calling clipr safely</h2> <p>To check whether the system has been properly configured to allow access to the clipboard, you may run <code>clipr_available()</code> which will either return <code>TRUE</code> or <code>FALSE</code>. This will be particularly useful for Linux-based systems, where clipr’s functionality depends on the installation of additional software. If you wish to display system requirements and configuration messages to X11 users, <code>dr_clipr()</code> will print these.</p> </div> <div id="interactive-non-interactive-use" class="section level2"> <h2>Interactive & non-interactive use</h2> <p>If you use clipr in your own package, <strong>you must not try to call it in non-interactive sessions</strong>, as this goes against <a href="https://cran.r-project.org/web/packages/policies.html">CRAN repository policy</a>:</p> <blockquote> <p>Packages should not write in the user’s home filespace (including clipboards), nor anywhere else on the file system apart from the R session’s temporary directory (or during installation in the location pointed to by TMPDIR: and such usage should be cleaned up). Installing into the system’s R installation (e.g., scripts to its bin directory) is not allowed.</p> <p>Limited exceptions may be allowed in interactive sessions if the package obtains confirmation from the user.</p> </blockquote> <p>For this reason, <code>write_clip()</code> will error by default in non-interactive use, which includes CRAN tests.</p> <p>If you want to use <code>write_clip()</code> non-interactively, you may either set the environment variable <code>CLIPR_ALLOW=TRUE</code> or call <code>write_clip(..., allow_non_interactive = TRUE)</code>.</p> </div> <div id="testing-on-cran-and-ci" class="section level2"> <h2>Testing on CRAN and CI</h2> <p>A few best practices will also help you responsibly test your clipr-using package on headless systems like CRAN or other testing infrastructure like Travis:</p> <ol style="list-style-type: decimal"> <li>Examples that will try to use <code>read_clip()</code> or <code>write_clip()</code> ought to be wrapped in <code>\dontrun{}</code></li> <li>Tests calling clipr should be conditionally skipped, based on the output of <code>clipr_available()</code>. This is necessary to pass CRAN checks, as otherwise <code>write_clip</code> will error out.</li> <li>If you are using <a href="https://travis-ci.org/">Travis.ci</a> to check your package build on Linux, consult the <a href="https://github.com/mdlincoln/clipr/blob/master/.travis.yml"><code>.travis.yml</code></a> for this package, which includes code for setting the <code>DISPLAY</code> and <code>CLIPR_ALLOW</code> environment variables, installing <code>xclip</code> and <code>xsel</code>, and running a pre-build script that will set up <code>xclip</code>/<code>xsel</code> to run headlessly.</li> </ol> </div> <div id="using-clipr-with-shiny" class="section level2"> <h2>Using clipr with Shiny</h2> <p>clipr won’t do what you expect when you call it with Shiny.</p> <p>clipr talks to the clipboard of the <em>system that is running R</em>. If you create a Shiny app and tell one of its functions to either read from or write to the clipboard, it can only access the clipboard of the server it is running on. R running on the <em>remote</em> server has no way to access the <em>local</em> clipboard belonging to your end user.</p> <p>However, you can instruct the user’s <em>internet browser</em> to write to the user’s clipboard by using <a href="https://cran.r-project.org/package=rclipboard">rclipboard</a>.</p> </div> <!-- dynamically load mathjax for compatibility with self-contained --> <script> (function () { var script = document.createElement("script"); script.type = "text/javascript"; script.src = "https://mathjax.rstudio.com/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML"; document.getElementsByTagName("head")[0].appendChild(script); })(); </script> </body> </html>