MIDI-Perl 0.77 (basically bugfix) entering CPAN

2000-05-20  Sean M. Burke  [email protected]

        * Release 0.77

        * Fixing an incidental bug in MIDI::Simple (which surfaces only
        in Perl 5.6, apparently).  Thanks to Matt Burt ([email protected])
        for finding the bug, as well as noting the fix.

        * Changed MIDI::Score::score_r_to_events_r and
        MIDI::Score::events_r_to_score_r (which were useful only in list
        context previously) to do something useful (and rather intuitive)
        in scalar context.


I.e., whereas they used to only do this:
 ($events_r, $ticks) = MIDI::Score::score_r_to_events_r( $score_r )
 ($score_r, $ticks) = MIDI::Score::events_r_to_score_r( $events_r )
They now also do this:
 $events_r = MIDI::Score::score_r_to_events_r( $score_r )
 $score_r = MIDI::Score::events_r_to_score_r( $events_r )
(Previously if you tried the calls with the latter, scalar, contexts, you'd get just the number "2" in $events_r or $score_r.)


Also added this rumination in the MIDI::Simple docs that may be of
interest to folks on the list:

(Author's note, two years later: all this business of returning lists
of various sizes, with this and other functions in here, is basically
a workaround for the fact that there's not really any such thing as a
boolean context in Perl -- at least, not as far as user-defined
functions can see.  I now think I should have done this with just
returning a single scalar value: a number (which could be 0!) if the
input is a number, and undef/emptylist (C<return;>) if not -- then,
the user could test:

      # Hypothetical --
      # This fuction doesn't actually work this way:
      if(defined(my $note_val = is_relative_note_spec($string))) {
         ...do things with $note_val...
      } else {
         print "Hey, that's no note!\n";
      }

However, I don't anticipate users actually using these messy functions
often at all -- I basically wrote these for internal use by
MIDI::Simple, then I documented them on the off chance they I<might>
be of use to anyone else.)


[This reminds me of the problem of returning multiple values in Lisp,
to which a long section in /The Evolution of Lisp/ is dedicated.
I have a PS and PDF copy in
 http://www.speech.cs.cmu.edu/~sburke/pub/
It's very intersting reading.]

--
Sean M. Burke  [email protected]  http://www.spinn.net/~sburke/