use strict;
use warnings;
use base 'Attribute::Default';
sub f : Default(undef,"xyz") {
  print("@_\nEND\n");
}
f('abc'); # 2nd argument defaults to xyz

##</code><code>##

# This is file Co.pm
package Co;
use strict;
use warnings;
use base qw(Exporter Attribute::Default);
our @EXPORT_OK=qw(f);
sub f : Default(undef,"xyz") {
  print("@_\nEND\n");
}
1;

##</code><code>##

# This is file cotest.pl
use warnings;
use strict;
use Co qw(f);
f('abc');

##</code><code>##

# This is file Co1.pm
package Co1;
use strict;
use warnings;
use Exporter;
use Attribute::Default;
our @ISA=qw(Exporter Attribute::Default);
our @EXPORT_OK=qw(f);
sub f : Default(undef,"xyz") {
  print("@_\nEND\n");
}
1;

##</code><code>##

# This is file cotest1.pl
use warnings;
use strict;
use Co qw(f);
f('abc');

##</code><code>##

Invalid CODE attribute: Default(undef,"xyz") at Co1.pm

##</code><code>##

# This is Co2.pm
package Co2;
use strict;
use warnings;
use Exporter;
our @ISA=qw(Exporter);
use base qw(Attribute::Default);
our @EXPORT_OK=qw(f);
sub f : Default(undef,"xyz") {
  print("@_\nEND\n");
}
1;

##</code><code>##

use warnings;
use strict;
use Co2 qw(f);
f('abc');

##</code><code>##

Can't locate object method "_ATTR_CODE_Default" via package "Co2"