It's not deprecated, in fact, it's very useful. But just because you can use a screwdriver to stir paint doesn't mean you should (JBYCDMYS, the complement to TMTOWTDI). The thing that cheeses me off about shift is that it actually modifies @_. Not that I care in most cases, but it seems like wasted effort, and programs are supposed to be efficient.

I find a few cases where shift is handy, though, such as in these highly simplified examples: 
sub new
{
    my $class = shift;
    my $self  = bless ({ @_ }, $class); # Hash-style params

    return $self;
}

sub fooge_default
{
     my $self = shift;

     $self->fooge(@_);  # Blind parameter passing
}

[download]
In most cases, though, you can just do direct assignment, mapping your params to @_ in a single declaration. If you have some sort of sick monstrosity that takes so many paramters you have to split up the declaration on to two lines, maybe you should re-think your interface. Once you're past six arguments, things get hard to parse.

As an example where shift is dangerous, consider this: 
sub fooge
{
     my ($foo, $bar) = (shift, shift);

     die "fooge() needs two arguments\n" unless (defined($bar));

     # ...
}

[download]
What's wrong with this? What if undef was a valid parameter? You've destroyed the evidence, so to speak. I'd try to use this instead: 
sub fooge
{
     my ($foo, $bar) = @_;

     die "fooge() needs two arguments\n" unless (@_ == 2);

     # ...
}

[download]
This version distinguishes between undef and not provided.

In reply to Re^4: Shifty Politics by tadman
in thread stoping and restarting a loop by mnlight

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