package deprecated;

use Carp qw/ carp croak /;
use vars '%subs';
sub import {
  my($good_self, @subs) = @_;
  my $pkg               = caller;

  *{"$pkg\::AUTOLOAD"} = sub {
    croak "unknown subroutine '$AUTOLOAD'"
      unless exists $deprecated::subs{$AUTOLOAD};

    carp "deprecated subroutine '$AUTOLOAD'";
    *$AUTOLOAD = $deprecated::subs{$AUTOLOAD};
    goto &$AUTOLOAD;
  } unless defined &{"$pkg\::AUTOLOAD"};

  for(@subs) {
    $subs{"$pkg\::$_"} = \&{"$pkg\::$_"};
    *{"$pkg\::$_"}     = *{"dummy_$pkg\_$_"};
  }
}

q[ the end is nigh ... ];
[download]

{
  package foo;

  sub func1 { print "old\n" }
  sub func2 { print "older\n" }
  sub func3 { print "new\n" }

  use deprecated qw/ func1 func2 /;
}

print "calling: func1\n";
foo->func1;
print "calling: func2\n";
foo->func2;
print "calling: func3\n";
foo->func3;

print "calling: func1 again ...\n";
foo->func1;

__output__

calling: func1
deprecated subroutine 'foo::func1' at deprecated_test.pl line 13
old
calling: func2
deprecated subroutine 'foo::func2' at deprecated_test.pl line 15
older
calling: func3
new
calling: func1 again ...
old
[download]

Briefly, what it does is create an AUTOLOAD method that will carp and then replace the dummy subroutine with the actual subroutine.