Nope, not really.

my %foo;
tie %foo, 'My::SpecialValidator';

sub bar : lvalue {
   $foo{bar};
}

package My::SpecialValidator;

sub STORE {
   my ($class, $attr, $value); 
   if ($attr eq 'bar' && $value !~ /^\d$/) {
       # exception.
   }

   ...
}
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