in reply to shift vs @_

This question is discussed at length in the excellent Perl Best Practices book in the third item of Chapter 9, "Argument Lists: Always unpack @_ first". Notice that this chapter is available free online as the book's sample chapter.

In this item, TheDamian argues that either version is acceptable, with the shift-based version preferred when one or more arguments needs to be sanity checked or documented with a trailing comment. The most important thing though, is to unpack them at the start of the subroutine and to avoid accessing them directly as $_[0], $_[1] etc.

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Re^2: shift vs @_
by shmem (Chancellor) on Oct 02, 2006 at 23:15 UTC
    just to prevent a perception of your statement as dogmatic -
    The most important thing though, is to unpack them at the start of the subroutine and to avoid accessing them directly as $_[0], $_[1] etc.

    - in most cases, yes. Operating directly on $_[0] is always fine if you know what you are doing, and why, e.g. the sub and the caller are designed that way to avoid costly copying. Whether in such cases a reference should be passed in the first place is another story. But then, $_[0] is a reference already...

    --shmem 

    _($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}
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