Generating a required package list

Hi,

I want to generate a list of required packages (including the one that
is already installed in the system) of a given package. Yum "deplist"
command seems to be a good start, it return a list of package that can
satisfy required dependency.  However, is it correct if I just grab
all unique and latest version of packages produced by that command?

I also look into yum resolveDeps() method, its logic for resolving
dependency is a bit more complex than that but I am not sure how can I
extract a list of required package during its execution.

Best regards,
Thawan Kooburat