$ perl -le " print foo bar "
Can't locate object method "foo" via package "bar" (perhaps you forgot to load "bar"?) at -e line 1.

$ perl -e "warn foo bar "
Can't locate object method "foo" via package "bar" (perhaps you forgot to load "bar"?) at -e line 1.

$ perl -e "warn bar->foo "
Can't locate object method "foo" via package "bar" (perhaps you forgot to load "bar"?) at -e line 1.