jucato@Suzaku:~$ cast -r -O ask-no yafray
Enter the root password, please.
Password:
Computing previously installed dependencies...
yafray preparing environment...
yafray checking dependencies...
yafray has a dependency on g++
yafray has a dependency on scons
yafray has a dependency on zlib
yafray has a dependency on jpeg
yafray has an optional dependency on ilmbase (for OpenEXR support)
Do you want to cast ilmbase? [n]

blender has a disabled optional dependency on yafray
Recast blender with dependency enabled? [n] y
g++ No work to do.
scons No work to do.
zlib No work to do.
jpeg No work to do.
Collating dependencies...
Spells are to be cast:
---------------------------
yafray

Do you want to cast these spells? [y]