Well, as pointed out, if you use parse (@_), you should see three lines, 2 from the initial call to parse, and one from the recursive call. If you examine carefully, you'll notice that the first Number: 0 comes from the recursive call, and the last Number: 0 is from the initial call, in the second iteration of the while.

So, what about doing this with &parse you may ask. Well, if you call from sub1, &sub2, then sub1 and sub2 will actually share @_! Look for instance at:

#!/usr/bin/perl

use strict;
use warnings;

sub foo {
    print "Foo: [@_]\n";
    shift;
}

sub bar {
    print "Bar: [@_]\n";
    &foo;
    print "Bar: [@_]\n";
}

bar 1, 2
 
__END__
Bar: [1 2]
Foo: [1 2]
Bar: [2]
[download]

Shifting off an element of @_ in foo() is noticeable in bar().

Leaves us the question, why three lines in perl -d:DProf test.pl when the function is called as &parse? For that, I do not know the answer. I can just guess that DProf puts each function in some kind of wrapper, causing the arguments to get duplicated.

Abigail