One minor quibble: the decision not to do common subexpression elimination actually predated tie and references. The main motivation for not doing it was that it was potentially an expensive optimization, and as a compile-and-go language, Perl could not afford any expensive optimizations that don't usually buy you much and can easily be emulated by hand coding anyway. Of course, as Perl moves more in the direction of precompiled modules, this policy will be subject to revision. (And this is also one of the reasons Perl 6 tightens up the rules on tying so that you can't tie a variable unless it has been declared as tieable, or even tied directly at declaration time.)

In reply to Re: Perl and common subexpressions by TimToady
in thread Perl and common subexpressions by Stevie-O

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.