To :D or not to :D

Newsgroups	perl.perl6.language
Date	2015-10-12 15:41 +0200
Subject	To :D or not to :D
Message-ID	<20151012134136.GE3111@moon.overmeer.net> (permalink)
Organization	MARKOV Solutions
From	mark@overmeer.net (Mark Overmeer)

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Hi all,

Liz and Tux demonstrate powerful Perl6 code at each monthly meeting of
our Mongers in Amsterdam.  Looking at their examples, I collected a few
questions of which I want to discuss the first one in this thread.


When I look at Merijns (Tux') code, I see a huge number of :D attributes.
    https://github.com/Tux/CSV/blob/master/lib/Text/CSV.pm

Close to all scalar positional parameter (51x) carry the :D flag.  I count
only 3 where the parameter does accept undef and the method is able to
handle it.  I count another 3 where the :D is missing, but the method is
not able the handle it.

The same for examples Liz shows us in our core code: most scalar
positional parameters have :D.

Writing a sub which is able to handle undef is usually more work than
implementing "I expect sane values for all of the parameters".


Questions:
  . are they using :D correctly?
  . the simpelest code does not handle the undef case... but now needs
    the more complex prototype to be correct.
  . it feels like the wrong default: usually you have to do something
    extra for the unusual cases, not the 90%+ usual cases.
  . :D looks really ugly, don't you think?  Try to explain to students
    to add this smiley everywhere.

Can someone explain this to me?  (Or point me to the correct place)
-- 
Thanks in advance

               MarkOv

------------------------------------------------------------------------
       Mark Overmeer MSc                                MARKOV Solutions
       Mark@Overmeer.net                          solutions@overmeer.net
http://Mark.Overmeer.net                   http://solutions.overmeer.net

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Thread

To :D or not to :D mark@overmeer.net (Mark Overmeer) - 2015-10-12 15:41 +0200
  Re: To :D or not to :D moritz@faui2k3.org (Moritz Lenz) - 2015-10-12 17:32 +0200
    Re: To :D or not to :D mark@overmeer.net (Mark Overmeer) - 2015-10-12 21:51 +0200
      Re: To :D or not to :D pmichaud@pobox.com ("Patrick R. Michaud") - 2015-10-12 15:25 -0500
        Re: To :D or not to :D darren@darrenduncan.net (Darren Duncan) - 2015-10-12 13:30 -0700
        Re: To :D or not to :D solutions@overmeer.net (Mark Overmeer) - 2015-10-13 00:32 +0200
          Re: To :D or not to :D pmichaud@pobox.com ("Patrick R. Michaud") - 2015-10-12 20:05 -0500
            Re: To :D or not to :D mark@overmeer.net (Mark Overmeer) - 2015-10-14 13:37 +0200
              Re: To :D or not to :D email@froggs.de (Tobias Leich) - 2015-10-14 14:11 +0200
      Re: To :D or not to :D moritz@faui2k3.org (Moritz Lenz) - 2015-10-13 09:17 +0200
        Re: To :D or not to :D mark@overmeer.net (Mark Overmeer) - 2015-10-13 10:41 +0200
        Backwards compatibility and release 1.0 rnhainsworth@gmail.com (Richard Hainsworth) - 2015-10-13 16:52 +0800
          Re: Backwards compatibility and release 1.0 darren@darrenduncan.net (Darren Duncan) - 2015-10-13 15:33 -0700
          Re: Backwards compatibility and release 1.0 moritz@faui2k3.org (Moritz Lenz) - 2015-10-14 11:54 +0200
            Re: Backwards compatibility and release 1.0 mark@overmeer.net (Mark Overmeer) - 2015-10-14 12:12 +0200
            Exploit the versioning (was Re: Backwards compatibility and release 1.0) darren@darrenduncan.net (Darren Duncan) - 2015-10-14 04:04 -0700
            Re: Backwards compatibility and release 1.0 Smylers@stripey.com (Smylers) - 2015-10-15 09:47 +0100
              Re: Backwards compatibility and release 1.0 email@froggs.de (Tobias Leich) - 2015-10-15 11:06 +0200
                Re: Backwards compatibility and release 1.0 liz@dijkmat.nl (Elizabeth Mattijsen) - 2015-10-15 12:42 +0200
                Re: Backwards compatibility and release 1.0 mark@overmeer.net (Mark Overmeer) - 2015-10-15 12:57 +0200
                Re: Backwards compatibility and release 1.0 liz@dijkmat.nl (Elizabeth Mattijsen) - 2015-10-15 13:13 +0200
              Re: Backwards compatibility and release 1.0 moritz@faui2k3.org (Moritz Lenz) - 2015-10-15 14:13 +0200
            Re: Backwards compatibility and release 1.0 rnhainsworth@gmail.com (Richard Hainsworth) - 2015-10-15 12:48 +0800

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