have_feature

have_feature(tag, rtype)

have_feature() Test for optional functionality / version info.

TorF = have_feature(tag)
TorF = have_feature(tag, toggle)
ver_str = have_feature(tag, 'vstr')
ver_num = have_feature(tag, 'vnum')
rdate = have_feature(tag, 'date')
all_info = have_feature(tag, 'all')
have_feature(tag, 'clear_cache')
have_feature('all', 'clear_cache')

Returns availability, version and release information for optional functionality. All information is cached, and the cached values returned on subsequent calls. If the functionality exists, an attempt is made to determine the release date and version number.

Inputs:

• tag (char array) – name to identify optional functionality

• toggle (-1, 0, 1) – numeric second argument, to turn optional functionality on or off

  toggle	return type	description and return value
  <none>	boolean	check availability, return true if available, false if not
  0	boolean	turn off optional functionality, return false
  1	boolean	turn on optional functionality, return true if available, false if not
  -1	boolean	toggle on/off state of optional functionality, return true if available, false if not

• rtype (char array) – string valued second argument determines which value is returned for available functionality, as follows:

  rtype	return type	description and return value
  'vstr'	char array	version number as a string
  'vnum'	double	version number as numeric value
  'date'	char array	release date
  'all'	struct	struct with all info (availablity, version numbers, release date)
  'clear_cache'	<none>	clears the cached information

Output:

• TorF (boolean) – true if optional functionality is available, false otherwise

• ver_str (char array) – version number as a string (e.g. '3.11.4')

• ver_num (double) – version number as numeric value (e.g. 3.011004)

• rdate (char array) – release date as a string (e.g. '29-Feb-2024')

• all_info (struct) – struct with fields:

  • av – availability, true if available, false otherwise

  • vstr – version as string

  • vnum – version as numeric value

  • date – release date as string

The optional functionality specified by tag can be toggled off or on by calling have_feature() with a numeric second argument toggle with one of the following values:

• 0 – turn off the optional functionality

• 1 – turn on the optional functionality (if available)

• -1 – toggle the on/off state of the optional functionality

Specifying the appropriate string value for the second argument allows have_feature() to return specific information about the functionality, if it is available. This includes the version number as a string or numeric value, the release date, or a struct with all of the above. For functionality that is not available, all calls with a string-valued second argument (except 'all') will return an empty value.

Finally, passing 'clear_cache' as the second argument will cause the cached information to be cleared for the specified tag or, if the first argument is 'all', for all optional functionality. When calling with 'clear_cache' no return value is defined.

For each valid value of tag, there is a corresponding feature detection function named have_feature_<tag>, where <tag> is the tag value for the feature in question. This makes have_feature() modular and extensible. Each feature detection function takes no input values, but returns three outputs:

• TorF – 1 = feature is available, 0 = feature is not available

• vstr – version number as a string (e.g. '3.11.4')

• rdate – release date as a string (e.g. '29-Feb-2024')

tag values for have_feature() detection functions included in MP-Test:

• 'matlab' – code is running under MATLAB, as opposed to Octave

• 'octave' – code is running under GNU Octave, as opposed to MATLAB

Examples:

if have_feature('matlab')
    disp(['Running MATLAB version ', have_feature('matlab', 'vstr')])
else
    disp(['Running Octave version ', have_feature('octave', 'vstr')])
end

See also have_feature_matlab(), have_feature_octave().