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

Comment on

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

Update: Please see Initial Devel::UncheckedOps, a macro for perl for notes on how print() can be overridden.


Its a function of toke.c's Perl_keywords() function. The keywords with positive values aren't overridable (so says pp.c's pp_prototype function). I get the impression from S_scan_inputsymbol that glob() and readline()'s overrideability is more a function of explicit support than something handled by the prototype. It also got the impression it might have something to do with print's status as an indirect object method expecting a list. Some guesses anyway.

Maybe this generalizes to: all functions overridable by CORE::GLOBAL:: have must prototypes or be explicitly supported by the perl parser (and the only known exceptions are glob() and readline()).

Added: For those that care, I pulled the list of keywords from toke.c:Perl_keywords() that are marked as not being overridable. You'll notice glob() and readmore() are in this list - again, it works only because of explicit support.

__DATA__ __END__ AUTOLOAD BEGIN CHECK DESTROY do delete defined END else eval elsif exists for format foreach grep goto glob INIT if last local m my map next no our pos print printf package prototype q qr qq qw qx redo return require s scalar sort split study sub tr tie tied use undef until untie unless while y

In reply to Re: !Overriding Builtin print by diotalevi
in thread !Overriding Builtin print by Zaxo

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!
  • 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?
    Username:
    Password:

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

    How do I use this? | Other CB clients
    Other Users?
    Others making s'mores by the fire in the courtyard of the Monastery: (10)
    As of 2015-07-31 19:05 GMT
    Sections?
    Information?
    Find Nodes?
    Leftovers?
      Voting Booth?

      The top three priorities of my open tasks are (in descending order of likelihood to be worked on) ...









      Results (280 votes), past polls