Using Timer and Classes

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0 个投票

I would like to use a timer to update the property (updateME)of a class using the function (updateMEFct). The way i did is not working properly and it certainly has to do on how i called the function in the timer (@(x,y)td.updateMEFct(td)). The function call of the timer should overwrite the instance of the class, but i don't know how to do that in this context.

here is the class :

classdef Updates
    properties
        t;        
        updateME;        
    end    
    methods
       %constructor
      function td = Updates(period)         
          td.updateME=100000;          
          td.t = timer('TimerFcn',@(x,y)td.updateMEFct(), 'Period', period,  ...
          'ExecutionMode', 'fixedRate');  
      end  
        function td=updateMEFct(td) 
          td.updateME=rand();       
        end      
        function start(td)
            start(td.t);
        end      
        function stop(td)
            stop(td.t);
        end
      end
  end

to launch the timer i used:

XX=Updates(5);
XX.start;

when i do that, updateME stays at 100000. if i call directly the function:

XX=XX.updateMEFct()

updateME changes.

Thanks for your help,

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Answer 1

per isakson 2012-3-3

在 MATLAB Online 中打开

0 个投票

The problem is that it is a value class and that you don't keep the updated object.

classdef Updates < handle

makes it work as you expect.

===============

Update:

With a value class it is possible to use assignin to save the updated object. However, to me that smells. I don't know if there is a "clean" way to do it.

function td=updateMEFct(td )
    td.updateME=rand();
    disp( [ datestr( now, 31 ), ': ', num2str( td.updateME ) ] )
    assignin( 'base', 'XX', td )
end
>> clear all
clear classes
XX=Updates(5);
XX.start;
2012-03-04 01:37:18: 0.25108
2012-03-04 01:37:23: 0.61604
2012-03-04 01:37:28: 0.47329
>> XX
XX = 
  Updates
    Properties:
             t: []
      updateME: 0.4733
    Methods

/ per

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bviguier 2012-3-4

using

classdef Updates < handle

is clearly the best answer,

many thanks isakson,

Daniel Shub 2012-3-4

Can you move the update about the handle class higher to the beginning of the answer, as to me that seems to be the answer. Your comment that the original code works is seems to be a red herring.

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Using Timer and Classes

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