mozilla/rust — pull request #7602 by blake2-ppc (2013-07-05 17:57:52+00:00)
Title: Implement .pop_opt() and .shift_opt() for vec

Implement methods .pop_opt() -> Option and .shift_opt() -> Option to allow retrieval of front/back of a vec in one operation without fail. .pop() and .shift() are changed to reuse the former two methods.

Follows the naming of the previous method .head_opt()