package MyApp::Local;
use strict;

sub umask {
  my($class, $umask) = @_;
  my $old = umask $umask;
  $class->new(sub { umask $old });
}

# ... and various other more application-specific methods

sub new {
  my($class, $cb) = @_;
  bless $cb, $class;
}

sub DESTROY {
  my $self = shift;
  $self->();
  undef;
}

1;