Why is Perl squashing my array?

Question

Here's a short test program:

sub foo($;@) {
  my $sql = shift;
  my @params = @_;

  print "sql: $sql\n";
  print "params: " . join(",", @params);
}

sub bar($;@) {
  foo(@_);
}

bar("select * from blah where x = ? and y = ?",2,3);
print "\n";

Why is the output this:

sql: 3
params: 

Rather than this?

sql: select * from blah where x = ? and y = ?
params: 2,3

Answer 1

It's because when you call foo(@_), the prototype for foo() forces the first parameter (which is an array) to be converted into a scalar (which is the number of elements in @_).

See answers to my previous question asking "Why are Perl Function Prototypes Bad"?

FWIW, you can keep the prototypes in place if you change bar thus:

sub bar($;@) {
    foo(shift, @_);
}

Answer 2

You're misunderstanding Perl prototypes. Remove them and it'll work fine.

See: Why are Perl 5's function prototypes bad?