for (my $i = 0; $i < scalar @{$self->{'trolley'}}; $i++) {
        if (${$self->{'trolley'}}[$i]->{'id'} eq $id) {
            $self->{'intent'} = undef;
            splice $self->{'trolley'}, $i, 1;
            return scalar @{$self->{'trolley'}};
        }
    }
[download]

That will not work correctly if you have more than one deletion.

Also, splice on an array reference will not work with all versions of perl.

This should be better:

    for ( my $i = $#{ $self->{ trolley } }; $i >= 0; --$i ) {
        if ( ${ $self->{ trolley } }[ $i ]->{ id } eq $id ) {
            $self->{ intent } = undef;
            splice @{ $self->{ trolley } }, $i, 1;
            return scalar @{ $self->{ trolley } };
        }
    }
[download]