tinsel-package {tinsel}

tinsel: Transform Functions using Decorators

Description

tinsel provides a decorator syntax for R allowing decoration and transformation of functions using #. comments.

Details

To the package in action save the code snippet below to a file, run source_decoratees on the file, and then call tmbg() or cats(5).

# emphasize text
emph <- function(f, style = '**') {
  function(...) {
    if (length(style) == 1) {
      paste(style, f(...), style)
    } else {
      paste(style[1], f(...), style[2])
    }
  }
}

#. emph
tmbg <- function() {
  'tmbg are okay'
}

#. emph(c('<b>', '</b>'))
cats <- function(n) {
  paste(rep('cats', n), collapse = ' ')
}

The call you make to tmbg is equivalent to emph(tmbg). The second example, cats(5), illustrates passing arguments to the decorator function.

While the above examples are small hopefully you begin to see how decorators may be used to transform or ensure function output without modifying the function's code by hand.