Overhaul @audioplayer class. Eliminate unnecessary input validation that one argument is supplied to class methods as interpreter guarantees the first argument is an @audioplayer object. Accept case-insensitive property names for get()/set() functions. Add BIST tests on a per function basis rather than only in @audioplayer constructor. * @audioplayer/__get_properties__.m: Eliminate nargin checking. Use intermediate variable hplayer to clarify code. Use ifelse() to simplify 5-line if/else/endif tree. * @audioplayer/audioplayer.m: Add input validation to prevent use of callback functions (not currently supported). Add FIXME note and comment out rudimentary support for callback functions. Remove tests of @audioplayer functionality to the methods files. Add input validation BIST tests for callback function validation. * @audioplayer/disp.m: Eliminate nargin checking. Mark file as tested for BIST. * @audioplayer/get.m: Rename "retval" to "value" in function prototype. Use input parameters with names matching documentation rather than varargin. Use new function getproperty() to do actual property retrieval rather than getfield(). Add BIST tests. * @audioplayer/get.m (getproperty): New function. Function checks property names without regard to case sensitivity and also issues a meaningful error message if the property name does not exist. * @audioplayer/isplaying.m: Eliminate nargin checking. Add BIST tests. * @audioplayer/pause.m: Eliminate nargin checking. Mark file as tested for BIST. * @audioplayer/play.m: Eliminate nargin checking. Use input parameters with names matching documentation rather than varargin. Use intermediate variable hplayer to clarify code. Mark file as tested for BIST. * @audioplayer/playblocking.m: Use input parameters with names matching documentation rather than varargin. Mark file as tested for BIST. * @audioplayer/resume.m: Eliminate nargin checking. Mark file as tested for BIST. * @audioplayer/set.m: Eliminate nargin checking of first argument. Use input parameter "player" for first argument rather than varargin. Use intermediate variable hplayer to clarify code. Add BIST tests. * @audioplayer/set.m (setproperty): Use lower() to implement case insensitive matching of property names. Rewrite error() message to be clearer and report the incorrect name. * @audioplayer/stop.m: Eliminate nargin checking. Mark file as tested for BIST. * @audioplayer/subsasgn.m: Change output variable name to "player" for clarity. Add BIST tests. * @audioplayer/subsref.m: Add BIST tests.

To cite GNU Octave in publications use:

  John W. Eaton, David Bateman, Søren Hauberg, Rik Wehbring (2020).
  GNU Octave version 6.1.0 manual: a high-level interactive language for
  numerical computations.
  URL https://www.gnu.org/software/octave/doc/v6.3.0/

A BibTeX entry for LaTeX users is:

  @manual{,
    title     = {{GNU Octave} version 6.3.0 manual: a high-level interactive language for numerical computations},
    author    = {John W. Eaton and David Bateman and S{\o}ren Hauberg and Rik Wehbring},
    year      = {2021},
    url       = {https://www.gnu.org/software/octave/doc/v6.3.0/},
  }

We have invested a lot of time and effort in creating GNU Octave, please
cite it when using it.  See also 'citation pkgname' for citing Octave
packages.