Well, it's almost 7 years later and Perl 6 is still a work in progress. But I know the answer to this issue: it works because the Int object is immutable. A Dog object can change its attributes, so two variables sharing the same object ($b=Dog::new;$a=$b;) will perceive the sharing. But an Int will never change. There are no mutating methods on it. Changing the value, e.g. ++$a, requires lvalue access to the variable, as this is $a= 1+$a; and assigns a different Int object to $a, leaving $b to still point to the original unchanged.

—John

In reply to Re: Perl6 - value vs. reference issues by John M. Dlugosz
in thread Perl6 - value vs. reference issues by John M. Dlugosz

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.