Is there a difference between Perl's shift versus assignment from @_ for subroutine parameters?

Question

Let us ignore for a moment Damian Conway\'s best practice of no more than three positional parameters for any given subroutine.

Is there any difference between the t

Answer 1

I would imagine the shift example is slower than using @_ because it's 6 function calls instead of 1. Whether or not it's noticeable or even measurable is a different question. Throw each in a loop of 10k iterations and time them.

As for aesthetics, I prefer the @_ method. It seems like it would be too easy to mess up the order of the variables using the shift method with an accidental cut and paste. Also, I've seen many people do something like this:

sub do_something {
   my $foo = shift;
   $foo .= ".1";

   my $baz = shift;
   $baz .= ".bak";

   my $bar = shift;
   $bar .= ".a";
}

This, IMHO, is very nasty and could easily lead to errors, e.g. if you cut the baz block and paste it under the bar block. I'm all for defining variables near where they're used, but I think defining the passed in variables at the top of the function takes precedence.