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You can tie in the attribute handler, so you can untie there, too. So, a closure sent as an extra argument to the constructor works:
#!/usr/bin/perl use warnings; use strict; use feature qw{ say }; { package Array::Nonempty::Attr; use Attribute::Handlers; sub Nonempty :ATTR(ARRAY) { my $referer = $_[2]; tie @$referer, 'Array::Nonempty', sub { untie @$referer } } } { package Array::Nonempty; use Tie::Array; use parent -norequire => 'Tie::StdArray'; use Carp; sub CLEAR { my $self = shift; $self->[0] = []; } sub TIEARRAY { my ($class, $untie) = @_; bless [ [], $untie ], $class } sub EXTEND { my ($self, $size) = @_; croak "Cannot be empty" if 0 == @{ $self->[0] } && 0 == $size; $self->SUPER::EXTEND($size); # Prevent "untie attempted while 1 inner references still exis +t" my $untie = $self->[1]; undef $self; $untie->() } } use parent -norequire => 'Array::Nonempty::Attr'; my %hash_ok = ( answer => 42 ); my %hash_empty = (); my @keys_ok :Nonempty = keys %hash_ok; say tied(@keys_ok) // 'not tied'; say for @keys_ok; my @keys_empty :Nonempty = keys %hash_empty;
($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord }map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,

In reply to Re^4: Declaring with my, assigning, and testing in same line (attributes) by choroba
in thread Declaring with my, assigning, and testing in same line by mordibity

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