in reply to Conditional initialisation

Wow. Thanks. The first two replies cleared up a few related uncertainties that were lurking in the background for me.

But the particular problem you cited is not actually something I would have run into myself, because I've never used that sort of idiom in a subroutine. So I'm curious... what's the motivation for doing this: 

my @list;
@list = @_ if ( @_ > 0 );  # (using the "safe" form)

# when no args have been passed, @list is empty (undef) at this point.
+..

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as opposed to doing this (which is what I always do, and I thought everybody always did it pretty much this way): 
my @list = @_;

# when no args have been passed, @list is empty (undef) at this point.
+..

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If there's a difference between those two, I'm having trouble seeing it. (Well, okay, with the former, one can easily fall into the trap that you described, but besides that, what's the difference?)

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Re: Re: Conditional initialisation
by Akhasha (Scribe) on May 25, 2004 at 01:44 UTC

    Ah, well the last time I used this construct it was for a function that could accept either a unix timestamp as a scalar, or a time vector as returned by localtime() or gmtime().

    So I was checking the length of @_ to see if it was greater than 1 (not 0), like this:

    sub unix_to_datetime {
  my @time_vec;
  @time_vec = @_ if @_>1;
  unless (@time_vec) {
    my $time = shift;
    @time_vec = (defined $time ? localtime($time) : localtime);
  }
  return strftime('%Y-%m-%d %H:%M:%S', @time_vec);
}

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      Wouldn't the following work just the same? 
      sub foo {
    my @time_vec = @_ > 1
        ? @_
        : defined $_[0]
            ? localtime($_[0])
            : localtime;

    return strftime('%Y-%m-%d %H:%M:%S', @time_vec);
}

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      ------
      We are the carpenters and bricklayers of the Information Age.

      Then there are Damian modules.... *sigh* ... that's not about being less-lazy -- that's about being on some really good drugs -- you know, there is no spoon. - flyingmoose

      I shouldn't have to say this, but any code, unless otherwise stated, is untested

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