Matlab defining class functions in an elegant way for OOP - matlab

Question

I am trying to implement a small example function in Matlab OOP.
The functioning code is:
classdef Cat < handle
properties
meowCount = 0;
end
methods
function obj = Cat() % all initializations, calls to base class, etc. here,
end
function Meow(obj)
disp('meowww');
obj.meowCount = obj.meowCount + 1;
end
end
end
I want to create something of the following sort akin to C++ as my real life function definitions are very big and I don't want to clutter my class definition:
classdef Cat < handle
properties
meowCount = 0;
end
methods
function obj = Cat() % all initializations, calls to base class, etc. here,
end
function Meow(obj);
end
end
%%
function Cat::Meow(obj)
disp('meowww');
obj.meowCount = obj.meowCount + 1;
end
So, basically write the definition of function Meow outside the class. How do I accomplish the above change ?
To play with the working first version you can use the following:
C = Cat;
C.meowCount
C.Meow

Answer 1

Create a folder called #Cat.
The within #Cat, put the following files:
Cat.m
classdef Cat < handle
properties
meowCount = 0;
end
methods
function obj = Cat()
end
Meow(obj) % this is optional, and just indicates the function signature
end
end
Meow.m
function Meow(obj)
disp('meowww');
obj.meowCount = obj.meowCount + 1;
end
Move out of the #Cat folder, and make sure it (or its parent folder) is on your path. Then try your examples.
If you use an # folder to contain your class like this, most methods (though not constructors, and not property get/set methods) can be moved to external files.
If you want, you can include a function signature with no implementation in the main classdef file. This is sometimes optional, but if you wish to change the Access level of the method away from default, it is necessary.

Answer 2

There are two ways of defining methods of a class. The newer, more portable way, is by defining them within the same classdef file. You can also write methods as separate M-file functions and put them in a #MyClass folder. Note that some methods must be in the classdef file. You can still define your separate file methods as static and private via helper functions. This is a bit of hack, which is why it's a good idea to put everything in the classdef file unless you have a very large project.

Answer 3

The best way to deal with clutter in your classdef file is to use code-folding. You can collapse individual methods and entire method blocks. In this way you can easily organize your classdef file to be as uncluttered as possible by grouping related methods together in the same methods block. Collapse any methods/blocks you aren't using at the time.
Additionally, you can use the "Go To" button in the Editor Ribbon Tab to select a specific method to view (if they are all defined in the same file).
Writing your methods in separate files may seem like a good solution at first, but if you have a class with many methods, it becomes extremely cumbersome to have many files open at once. Unlike C++, you can only define one method per file. It really ends up being quite a mess.
See Also:
Code Folding — Expand and Collapse Code Constructs
Editor/Debugger Code Folding Preferences