Constructor behaviour in Classes

Main Question: Is this normal behaviour?

I've encountered some strange behaviour when initilizing properties of classes (child of handle):

Note: example test-script in zip-file (attachement)

classdef pokemon< handle % baseClass
  %POKEMON container
  %   dummy example

    properties
        moves = Moves() ; %Moves is also a (custom) class (child from handle)
        level;
    end

    methods
        function obj = pokemon(obj)
          %  obj.moves = Moves(); % if the property is initialized here, it
          %  works likes excepted.
        end
        function getname(obj)
            % does nothing
        end
    end
end

When a property is initilized in the 'properties' section:

A= Pokemon; B = Pokemon;

The handle of A.moves and B.moves is the same. ( change A.moves, B.moves also changes)

If the property is initilized in the constructor (like I would normaly do), A.moves and B.moves are two different objects.

Sub-Question: Why does it behaves differently?

Answer 1

[Guillaume]

This is normal behaviour and 'documented' (but extremely hard to find in the doc even when you what you're looking for!)

See When MATLAB Evaluates Expressions.

Basically, all initialisations in a property section is done only once, when the class is loaded (i.e first use). After that the initialisation value is shared by all instances. It only matters when the initialised property is a handle class, and indeed for these you must initialise the property in the constructor.