I saw kennethk's reply after posting my own. I followed the first link provided and found a much easier fix, without the need for my BEGIN block, at the end of that thread (Re^2: Underscores changed to hyphens by HTTP::Proxy header filter): 

$r->header(':__X_Y__', 1);

[download]

It also mentions why $TRANSLATE_UNDERSCORE has been undocumented, so there's probably little point in requesting a "documentation enhancement" such as I suggested.

There's no mention of using the colon prefix in the documentation for the header() methods of either HTTP::Request or HTTP::Headers. The latter could probably at least supply a link to the short section, right at the end of its doco, which explains it: "NON-CANONICALIZED FIELD NAMES".

"... (convenience features that change data should be explicitely turned on, rather than turned off) ..."

In general, I'd agree with that statement. In this specific case, I'm not so sure: that particular feature is, I suspect, exactly what the vast majority of users want; I've certainly never needed it to work differently. Having said that, I do think such features need to be well documented: in this instance, it probably just needs a short sentence with a L<...> added to the POD.

Update (fix): Oops! I left out a word which completely changed the intended meaning: s{I'm so sure}{I'm not so sure}.

— Ken

In reply to Re^3: double underscore in http-header by kcott
in thread double underscore in http-header by morgon

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.