Slash Style Guide: Coding Principles 2 Lexical Variables globals are never used where a lexical or local() will work don't use 'our' because it requires 5.6 Pass by Reference arrays and hashes are passed by reference only. All object classes must provide a DESTROY method. If it doesn't do anything, provide it anyway. sub DESTROY {}; Do not use __END__ or __DATA__ because they break mod_perl. Do not use die() or exit() ever in slash web-based programs. (see above about throwing exceptions in Ensembl; slash doesn't explicitly talk about exception handling) Do not use shift, use @_ because it is faster.