Beefy Boxes and Bandwidth Generously Provided by pair Networks
Welcome to the Monastery

comment on

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

I'm the wrong person to ask, but I would assume so, as they (substr refs) have steadily been corrected and improved over the last few versions.

They have been available since before my time (5.6.1), but through a bug in the implementation, there was originally only 1 lvalue ref available at a time for each given string in te program. This was fixed in 5.8.5.

The most useful use of them is processing fixed length record files where you allocate the input buffer and create an array of lvalue refs to the fields. You can now read or sysread subsequent records directly into the buffer overlaying the previous record, and the fields array now refers to the fields of the new record.

It saves re-divvying the buffer over and over for each record, which can save a good deal of memory (re)allocation when processing large files. Add a few seeks and you have an efficient and fairly cache freindly way of doing in-place editing on huge, fixed record length files.

Not they're much in vogue these days, but they do have their uses :). I played with manipulating huge tiff images like this one (Warning!!! 11,477 x 7,965 x 24 image 204MB) directly on disk.

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
Lingua non convalesco, consenesco et abolesco. -- Rule 1 has a caveat! -- Who broke the cabal?
"Science is about questioning the status quo. Questioning authority".
The "good enough" maybe good enough for the now, and perfection maybe unobtainable, but that should not preclude us from striving for perfection, when time, circumstance or desire allow.

In reply to Re^3: lhs substr(): refs vs. scalars by BrowserUk
in thread lhs substr(): refs vs. scalars by renodino

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 taking refuge in the Monastery: (8)
    As of 2019-06-26 21:57 GMT
    Find Nodes?
      Voting Booth?
      Is there a future for codeless software?

      Results (111 votes). Check out past polls.