il Thu, 17 Jun 2004 00:10:40 +0900, Florian Weber
<csshsh / structbench.com> ha scritto::

>hi!
>
>i have a design question. for example i have a class which reads a file
>and prints out each line with line numbers. what if now i wanna be able
>to plugin some functionality which sorts the file, depending on some
>conditions (extension, etc) before its passed on to the line numbering
>functionality. the class should be as less tied as possible to the 
>sorting
>functionality as possible..
>
>how would you normally design that in ruby?

I'd say that you could use some kind of pattern and so on. 
You may find this thread useful:
http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/48648

As of now I'd probably use some trick similar to this:
http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/97440

to allow the user to write something like add_filter(:read) do.. end