If you want to validate your object, just check!

sub new {
  #...
  bless $self, $class;

  for my $check (qw(func1 func2 rarelyused)) {
    die "$class doesn't have method '$check'" unless $self->can($check
+);
  }
}
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Of course, even then, if $class actually has an AUTOLOAD function, can doesn't play nice with that, and you end up thinking it can't do something when it can, just fine, through the AUTOLOAD method.