a neat ruby idiom

[rgrau] guys, I just learned a new idiom  
[rgrau] (@foo ||= []) << bar  
[michal] :)  
[rgrau] It's not crystal clear, but I like it  
[rgrau] my perl background damaged my brain beyond repair
[jakub] rgrau: idiom or idiot?
[rgrau] you pick
[jakub] ok, done
[rgrau] I know which one you picked  
[jakub] u r smart
[rgrau] u idiom
[rgrau] that log goes to my blog inside ruby section