>>>>> "Florian" == Florian G Pflug <fgp / phlo.org> writes:

    Florian> Can I derive Classes from Classes defined in a
    Florian> c-extension of ruby (such as the mysql - library)?

Yes

    Florian> I tried it, and it works, but it seems I cannot overload
    Florian> the initialize funktion (aka the constructor)

It is possible the c-extension is not properly invoking "initialize"
internally.  The Extending Ruby chapter in the "Programming Ruby" book
covers this with good examples.  The web reference is

    http://www.rubycentral.com/book/ext_ruby.html

Look for the section entitled "Wrapping C Structures".  Toward the end 
of that section, there is a discussion of the "rb_obj_call_init"
function.

-- 
-- Jim Weirich     jweirich / one.net    http://w3.one.net/~jweirich
---------------------------------------------------------------------
"Beware of bugs in the above code; I have only proved it correct, 
not tried it." -- Donald Knuth (in a memo to Peter van Emde Boas)