Classdef

This page is a stub. We should begin documenting what classdef is implemented and what is not.

Not Supported

• enumeration

See #44582 and help implementing it.

• build-in class as superclass

classdef nonsense < uint32

end

See #44035

• concatenating objects into array of objects.

Example:

classdef MyClass < handle
end

c = MyClass();
cc = [c, c];   % won't work

For now you can use a cell-array of objects instead:

cc = {c, c};   % ok

Also see #44665

• Immutable property set access.

Example:

classdef MyClass < handle
    properties (SetAccess = immutable)
        x
    end
    methods
        function obj = MyClass()
            x = rand();
        end
    end
end

Use "private" properties as workaround.

• Function handles to package methods and static class methods.

For example if we have +mypackage/myfunc.m, creating a function handle as fh = @mypackage.myfunc won't work. As a workaround, we can create an indirection using an anonymous function fh = @(varargin) mypackage.myfunc(varargin{:}). Similarly for static class methods where fh = @MyClass.myfunc isn't yet supported. Another workaround for package function handles is to use str2func, e.g. fh = str2func ("mypackage.myfunc").

A fuller example is also given below:

classdef method_function_handle_test

%  properties
%  
%  
%  end
  
  properties (Hidden, SetAccess = protected)
    hfoo = [];% handle to function
  end
  
  methods
  
    function self = method_function_handle_test ()
      self.hfoo = @foo;    
    end
    
    function bar (self)
        self.hfoo (self); 
    end

  end
  
  methods (Hidden, Access = protected)
    function foo (self)
      disp ('hello!');
    end
  end

end

Then running:

>> x = method_function_handle_test
error: @foo: no function and no method found
error: called from
    method_function_handle_test at line 17 column 17
stopped in <****>/scratch/mfiles/octave_tests/method_function_handle_test.m at line 17
17:       self.hfoo = @foo;

See #45351

• Defining local functions in the same classdef-file is not working.

For example, the following code gives a syntax/parse error:

classdef MyClass
    methods
        function obj = MyClass()
            myfunc()
        end
    end
end

function myfunc()
    disp('myfunc')
end

See #41723.

• debugging in classdef methods (and +package directory functions)

Breakpoints cannot currently be set in classdef methods from the gui, but only from the command line:

dbstop @aclass\amethod

See #45404

• Saving/reading classdef objects to/from (.mat) file

Supported

• methods
  • static
  • private

• properties
  • SetAccess (public/private/protected)

Open Bug Reports

Function handles and classdef methods

• 48802 function overload resolution on function handles fails on classdef methods defined in class body
• 46659 classdef: cannot create handles to functions in +package
• 45351 function handles to classdef methods not supported
• 51709 Creating function handle to static methods
• 47680 classdef @ operator to overrided superclass methods

Issues with basic classdef functionality

• 42510 methods() does not return functions defined in classdef file
• 51659 Calling 'methods' on self causes syntax error
• 53614 classdef properties() function not implemented
• 46387 Display class properties
• 48682 print_usage fails within classdef block
• 55223 can't subsasgn with 2-level index (curly braces + parentheses) with classdef handle
• 49434 which returns "built-in function" for classdef m-file
• 48041 classdef: `help myclass` messes up `help @myclass/method`
• 43047 help() does not see classdef files
• 42620 exist() does not use "class" argument
• 53874 doc_cache_create doesnt handle classdef documentation
• 52096 meta.class.fromName throws error when class name not found.
• 51377 Parse error for abstract methods
• 45457 Incorrect behavior of constant classdef properties referencing other constant properties in the same block
• 44665 error in concatenation of classdef objects
• 44582 classdef: missing support for enumeration
• 44036 interpreter does not recognize classdef (syntax error)
• 48693 classdef subsref method is not called with correct nargout value

Classdef and +package directories

• 54941 interpreter cannot find methods in files of classdefs in packages
• 54273 Can't access properties of class in package in function defined in class

Arrays of classdef objects

• 53906 Cannot make an object array with square brackets
• 47755 Access to object arrays
• 47241 classdef: assigning property of handle object in object array constructs new object

I/O issues

• 55497 No or wrong default file name when saving a classdef file
• 45833 support load/save of classdef objects

Debugger

• 46451 unable to set breakpoints within classdef classes
• 45404 Breakpoints cannot be set in classdef methods or +package function files

Lower-priority issues

• 55488 Invalid use of colon char as classdef function's argument when subsref is overwritten
• 55487 ismethod of custom classdefs always returning false
• 54966 Error when assigning array to an object implementing subsasgn() subscripted using "{}"
• 54783 subsasgn call when the subscripted expression contains the end keyword
• 54028 copy of non-handle class instance is not deep
• 53811 cellfun does not find overloaded function with function name argument
• 52989 classdef: missing error messages on multiply defined properties
• 52614 setting properties of classdef object during construction with inheritance
• 52582 Dependent constant properties in classdef errors: no such file
• 52123 Indirect memory leak in cdef_manager::initialize ()
• 51285 max_recursion_depth error in classdef constructor
• 50395 subclassing a class that is also defined as a variable fails
• 50011 failure to report error on conflicting methods for classdef
• 49379 classdef constructor: .argn. loses first argument, inputname(n) returns inputname(n+1)
• 46652 whos bytes property not right for classdef classes
• 45893 classdef properties are not reloaded when file is updated
• 44934 classdef parser prints extra newline when failing to parse bad classdef file
• 44643 classdef handle object can go into an recursive loop with isequal(obj1,obj2) if both are self-referential
• 44035 classdef is unable to to subclass double

Documentation

• 50729 Improve OOP documentation
• 47908 Octave:classdef-to-struct not documented in warning_ids.m
• 44590 More documentation for the current status of classdef implementation

Classdef examples in the wild

• http://hg.savannah.gnu.org/hgweb/octave/file/tip/scripts/general/inputParser.m
• http://hg.savannah.gnu.org/hgweb/octave/file/tip/scripts/%2Bcontainers/Map.m
• https://github.com/markuman/go-redis
• https://github.com/PetrKryslUCSD/FinEALE