Icky hack (local ... for ...;): 
sub Dump {
    my @opts;
    for my $option (@dump_options) {
        no strict 'refs';
        my $ref = \${$implementation.'::'.$option};
        push @opts, [ $ref =>
            defined($$ref) ? $$ref : ${"YAML::$option"},
        ];
    }
    local ${$_->[0]} = $_->[1] for @opts;
    return &{"$implementation\::Dump"};
}

[download]

Sticking to something that won't break: 

{
    package YAML::OnScopeExit;
    sub DESTROY { ${ shift() }->() }
}

sub _on_scope_exit(&) {
    my ($sub) = @_;
    return bless(\$sub, 'YAML::OnScopeExit');
}

sub Dump {
    my @opts;
    for my $option (@dump_options) {
        no strict 'refs';
        my $ref = \${$implementation.'::'.$option};
        push @opts, [ $ref =>
            defined($$ref) ? $$ref : ${"YAML::$option"},
            $$ref,
        ];
    }

    my $sentinel = _on_scope_exit {
        ${$_->[0]} = $_->[2] for @opts;
    };

    ${$_->[0]} = $_->[1] for @opts;

    return &{"$implementation\::Dump"};
}

[download]

Both untested.

In reply to Re: Bug in YAML::Any - What to do? by ikegami
in thread Bug in YAML::Any - What to do? by bv

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.