It is basically a reconstruction (from memory, and incorrectly) of the slurp idiom discribed and discussed in Cheap idioms. I suggest you read that thread as it goes into great detail and discusses all the pros and cons.

I would also recommend that if you are using the one I (mis)typed in my posts (as a substitute for the one I call from my personal Utils library), that you either replace it with the final concensus form from that thread, or just install File::Slurp and have done with it.

Update: Indeed, I strongly suggest that you get File::Slurp and substitute it's slurp() routine. It is far faster than the slurp routine in the Cheap Idioms thread.