Beefy Boxes and Bandwidth Generously Provided by pair Networks
good chemistry is complicated,
and a little bit messy -LW

Comment on

( #3333=superdoc: print w/ replies, xml ) Need Help??

So why does perl make copies instead of real references when you think your making a reference?

$s = $x . $y;

Wouldn't it be nice if concat didn't have to allocate a scalar that will just end up being copied into $s and deallocated?

Well guess what, it doesn't. That instance of the concat operator will always return the same scalar. This saves allocating a scalar and deallocating a scalar.

But of course, doing that alone would break weird code like following:

my @b = map { \($prefix.$_) } @a;

So the deref operator must be complicit and make a copy of the scalar if it comes from concat.

Why doesn't entersub clone PADTMPs into unique mortal SVs if PADTMPs are found on the stack automatically

Cause that defies the whole point of avoiding the creation of those scalars.

Shouldn't making a ref in XS be identical to making a ref in Perl?

Sure, but it's not Perl's fault your XS code isn't identical to its code.

Should there be a function for creating references that checks PADTMP? Maybe. Yes, p5p would be appropriate for this.

In reply to Re^3: lexicals are all the same scalar and never go out of scope? by ikegami
in thread lexicals are all the same scalar and never go out of scope? by patcat88

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, 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, 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.
  • Log In?

    What's my password?
    Create A New User
    and the web crawler heard nothing...

    How do I use this? | Other CB clients
    Other Users?
    Others musing on the Monastery: (1)
    As of 2015-11-27 00:43 GMT
    Find Nodes?
      Voting Booth?

      What would be the most significant thing to happen if a rope (or wire) tied the Earth and the Moon together?

      Results (710 votes), past polls