为什么属性不从类方法接受一个新的值？ [英] why do properties not take on a new value from class method?

问题描述

我想更多地了解Matlab类及其属性。这是我创建的测试类：

  classdef Test 
 properties 
％网络类型的属性
 some_var 
 end 
 
方法
函数N = Test（）
 end 
 
 function change_var（N，val）
 N.some_var = val; 
 end 
 end 
 end 
  

现在， ，并调用change_var（）...

 > a =测试; 
>> a.change_var（2）; 
>> a.some_var 
 
 ans = 
 
 [] 
  

为什么属性some_var不在赋值中的值val上？

解决方案

$ c> Test 类已定义为价值类到句柄类。有效地，当调用 a.change_var 时，按$值传递 a 。要将更改存储到 some_var 属性，请执行以下操作：

 
 >> a =测试; 
 >> a = a.change_var（2）; 
 

另一种方法是使 Test 一个句柄类，你的问题会按照你的预期工作。为此，通过将类定义的第一行改为：

<$ p $类继承句柄 p>
classdef Test< handle

I am trying to understand a little bit more about Matlab classes and their properties. Here is a test class I have created:

classdef Test    
    properties
         % Properties of the network type
        some_var
    end

    methods
         function N = Test()
         end

        function change_var( N, val )
             N.some_var=val;
        end
    end
end

Now, I create an instance of this class, and call "change_var()"...

>> a=Test;
>> a.change_var(2);
>> a.some_var

ans =

     []

Why has the property "some_var" not taken on the value "val" in the assignment?

解决方案

The Test class has been defined as a value-class as opposed to a handle class. Effectively, when you call a.change_var, a is passed in by-value. To store the change to the some_var property do this:

>> a = Test;
>> a = a.change_var(2);

The alternative is to make Test a handle class in which case the example in your question would work as you expected. To do this, inherit from the handle class by changing the first line of your class definition to this:

classdef Test < handle

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