如何将侦听器设置为 MATLAB 对象的结构字段

Question

我有一个MATLAB对象，类似于:

classdef myObj < handle
properties (SetObservable)
    % NOTE: we want this to be a struct, as written, its not
    myStruct
end
methods
    function self = myObj(fieldVal)
        self.myStruct = fieldVal;
        % WANT: self.myStruct.myField = fieldVal;
        %  add listener to update if change to self.myStruct
        % WANT: add listener to update if change to
        % self.myStruct.myField
        addlistener(self, 'myStruct', 'PostSet', @self.callbackFnc);
    end
    function callbackFnc(self, varargin)
        fprintf(['self.myStruct is now ', num2str(self.myStruct), 'n'])
    end
end
end

它有一个监听器，监听一个实例的属性(乐观地命名为myStruct)。这给了:

>> tempObj = myObj(3);
>> tempObj.myStruct = 4;
self.myStruct is now 4

如何将侦听器设置为self.myStruct而不是self.myStruct本身的字段?

Answer 1

你不能直接做你想做的事。您只能将侦听器附加到属性本身，而不能附加到属性的字段(如果属性是结构体)。

我会尝试做一些稍微不同的事情，使用myStruct属性的set函数来检测正在设置的字段，然后触发常规事件而不是属性事件:

classdef myObj2 < handle
properties
    myStruct = struct('myField', []);
end
events
    myFieldChanged
end
methods
    function self = myObj2(fieldVal)
        self.myStruct.myField = fieldVal;
        addlistener(self, 'myFieldChanged', @self.callbackFnc);
    end
    function set.myStruct(obj, val)
        oldProp = obj.myStruct;
        obj.myStruct = val;
        if obj.myStruct.myField ~= oldProp.myField
            notify(obj,'myFieldChanged')
        end
    end
    function callbackFnc(self, varargin)
        fprintf(['self.myStruct.myField is now ', num2str(self.myStruct.myField), 'n'])
    end
end
end

希望这个建议有帮助!