This package uses libinline-ruby, a Ruby module that allows for easily
embedding and on-the-fly compiling C code in Ruby modules.

Although it will work right away on most typical situations, there are
a couple of catches you should keep in mind:

- To minimize startup times, the inlined C code is cached. This means,
  any user who calls this module in his Ruby code will get a directory
  called ".ruby_inline" on his home directory. Inside this directory,
  Inline will store the C code to be compiled and the compiled
  objects. The directory can be safely purged, as it will be
  regenerated as needed.

- You can set up the environment variable INLINEDIR to specify a
  different directory, i.e., to cope with the cases where the current
  user has no rights to write on his own directory (which is often the
  case when using this module for Web-facing application servers). You
  can safely point it to a randomized temporary directory, as in:

  $ su - nobody -c 'export INLINEDIR=$(mktemp -d); \
         ruby -e "require \"image_science\""; \
         rm -rf $INLINEDIR'

  Of course, you would replace the call to Ruby to the startup for
  your application. There will be a slight time penalty upon
  initialization, as this will compile anew the code each time it is
  started, but will allow you to work with users unable to work in
  their home directories.

- It might also be a good idea, specially on slower systems, to set
  INLINEDIR to a fixed location, i.e. to create user-owned
  /var/lib/inline/$(whoami) directories. This would avoid the
  recompilation penalty - You should just remember to purge the
  directory should you stop using this module.

Of course, for most use cases, the default .ruby_inline directory will
serve you well.

 -- Gunnar Wolf <gwolf@debian.org>, Wed, 14 Sep 2011 17:02:08 -0500
