Distributing native and ruby version of a library


#1

Hi,

I have a simple library, one in a pure ruby version and one in a
ruby/c version (which is quicker). I would like to distribute both and
let the user decide (by checking whether a c library is available)
which version to install. What would a clever way to accomplish that?
Should I make the decision when running extconf.rb? Any hints?

Patrick

(the directory structure so far)

rb/mylib.rb

c/mylib.rb
/mylib_base.c
/extconf.rb

both should be used by require ‘mylib’ or alike.


#2

In article removed_email_address@domain.invalid,
Patrick G. removed_email_address@domain.invalid wrote:

(the directory structure so far)

rb/mylib.rb

c/mylib.rb
/mylib_base.c
/extconf.rb

both should be used by require ‘mylib’ or alike.

How about in your rb/mylib.rb file you do something like:

begin
require ‘ext/mylib_base’
rescue
require ‘lib/mylib_base’
end

Where ext/mylib_base would be the shared lib created from the C file and
lib/mylib_base would be the Ruby implementation.

The user of mylib just does:

require ‘mylib’

…and it’s all transparent to the user whether or not the C version or
the
ruby version is used.

Phil


#3

Well, last guess before I head to bed:

In “mylib.rb”:

begin
require “mylib_impl_c” # Attempts to load the C shared library.
rescue LoadError
require “mylib_impl_rb” # Falls back to the ruby implementation.
end

Yay for gracefully degrading functionality. Or performance, for that
matter.
Sprinkle with configuration parameters to let user determine at runtime
which
backend to use to taste.

David V.

DÅ?a Streda 08 Február 2006 20:58 Patrick G. napísal:


#4

Hi Phil (and David),

[…]

The user of mylib just does:

require ‘mylib’

…and it’s all transparent to the user whether or not the C version or the
ruby version is used.

OK, that makes sense. Thanks. I wonder if this could be combined with
the setup.rb from RAA (http://raa.ruby-lang.org/project/setup/3.2.4

When I run

ruby setup.rb config

setup.rb tries to create the c-extension in ext/mylib/… but this
might fail if the user doesn’t have the necessary libraries installed.
Is there a way in setup.rb to say ‘keep going if you can’t create the
c extension’? I mean as a configuration file or alike, not as a
parameter passed to setup.rb. This way the c-extension will installed
only if available.

Patrick