Calling Foo::new() calls the function new in the package Foo as a direct function call. It doesn't magically put the class name in the first element of @_ in Foo::new(). The call is completely different.
This example will show that:
# this is the file Foo.pm
package Foo;
use strict;
use warnings;
sub new {
my $class = shift @_;
print "class = $class\n";
my $self = {};
return bless $self, $class;
}
1;
# heres a test program using it, called foo_test.pl
#
#!/usr/bin/perl
use strict;
use warnings;
use Foo;
use Data::Dumper;
{
print "Arrow test:\n";
my $regular_foo = Foo->new();
print Dumper($regular_foo);
print "\n\nColon test:\n";
my $colon_foo = Foo::new();
print Dumper($colon_foo);
}
And heres the output from running foo_test.pl
Arrow test:
class = Foo
$VAR1 = bless( {}, 'Foo' );
Colon test:
Use of uninitialized value in concatenation (.) or string at Foo.pm li
+ne 9.
class =
Use of uninitialized value in bless at Foo.pm line 13.
Explicit blessing to '' (assuming package main) at Foo.pm line 13.
$VAR1 = bless( {}, 'main' );
I use the most powerful debugger available: print!