package Obj;

# Class variable
%handlers=();

sub new {
  my $class = shift;
  my $self = { @_ };
  bless $self, $class;
  $self->set_signal_handlers;
  $self;
}

sub name {
  shift->{'name'};
}

sub set_signal_handlers {
  my $self = shift;
  if (!%handlers) {
    # Class signal handler, only set the first time
    $SIG{USR1} = \&class_handle_USR1;
  }
  # You could index by $self->name, or by any other identifier
  $handlers{$self} = sub { $self->handle_USR1() };
}

sub handle_USR1 {
  my $self = shift;
  print "handling USR1 for ", $self->name, "\n";
}

sub class_handle_USR1 {
  foreach (keys %handlers) {
    &{$handlers{$_}}();
  }
}

package main;

my $obj1 = new Obj(name => 'obj1');
my $obj2 = new Obj(name => 'obj2');

while (1) { }