Lexical scoping has almost nothing to do with Perl's ability to close file handles as you describe. As others point out, it's RAII with reference-counted garbag

Lexical scoping has almost nothing to do with Perl's ability to close file handles as you describe. As others point out, it's RAII with reference-counted garbage collection. This feature is not-thread safe, which is one reason why perl threads require making an entire copy of the whole program state and treating shared variables specially. The former makes perl threads a mostly useless abomination and the latter causes other problems. For instance, a friend of mine at work who didn't know the full details of perl threads couldn't figure out why his threaded program was running abysmally slow and using tons of memory. When he found out, he ended up just switching to a forking process model. As for the specialness of shared variables, another friend of mine wrestled with the fact that the perl serialization libraries for whatever reason couldn't handle serializing shared variables and he as far as I know never found a way to solve the problem. Bottom line, Perl's morass of bad language design leads to lots of problems that more elegant solutions like ruby's blocks can avoid. Also, reference counting is considered computationally less efficient than global garbage collectors. See the recent paper Myths and realities: the performance impact of garbage collection, which shows that a reference-counting garbage collector performs significantly worse than a mark-and-sweep algorithm.