[chef] Is attribute values combination accross cookbooks possible?

[Ares < >]

Hello,

I've got two cookbooks, one is for managing firewall and second is for let's 
say apache for example. Firewall cookbook defines attribute :ports which is 
an 
array of ports that should be open.

Is there any way how apache can add it's :listen_port to array of :ports? It 
should first verify, that attribute :ports exists then check whether the port 
is already in array and finally add it if it's missing.

Thanks for any reply

ares