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, @_); }