title: Including hpp files in an R package
body: <p>I'm writing an R package making use of Rcpp to call functions written in C++ into the R code. Some of these functions and templates are written in files with a .hpp extension following the convention used by boost (and also discussed <a href="https://stackoverflow.com/questions/152555/h-or-hpp-for-your-class-definitions">here</a>).</p>
  <p>This does not result in an error when building (<code>R CMD build .</code>) and checking (<code>R CMD check --as-cran package.tar.gz</code>) the package, but it returns the next warning:</p>
  <pre><code>Subdirectory ‘src’ contains:
    file.hpp example.hpp
  These are unlikely file names for src files
  </code></pre>
  <p>Ok, this is not a big issue, but my concern is, <strong>why</strong> the warning? is naming *hpp files considered a bad practice in the R community? Are there objective  or community reasons why I should use *cpp/*h files instead of *hpp for the templates?</p>