This patch is required to build rudl with ruby 1.9.1 (p243). (along with the gcc4 patch from #1670574)
RARRAY(foo)->len becomes RARRAY_LEN(foo),
RSTRING(foo)->len becomes RSTRING_LEN(foo),
RSTRING(foo)->ptr becomes RSTRING_PTR(foo)
I've tested this with my own little rudl game and it works fine so far.