Sounds good; but, if I add

Internals::SvREADONLY($_, 0);

[download]

to the code I gave above, immediately before the line $_ = 'fred';, I still get:

 1:03 >perl 723_SoPW.pl
literal1
Modification of a read-only value attempted at 723_SoPW.pl line 26.

 1:03 >perl -v

This is perl 5, version 18, subversion 1 (v5.18.1) built for MSWin32-x
+86-multi-thread-64int
...

[download]

Also, where and how can I learn about a feature that is “intentionally-undocumented”? (This is a serious question!)

Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

In reply to Re^4: How to safely use $_ in a library function? by Athanasius
in thread How to safely use $_ in a library function? by perl-diddler

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.