Matlab calsses - PreGet listener on structures

Hello,

I am using some basic Matlab classes with some dynamic defined properties. I added listeners 'PreGet' and 'PostGet' for a property. My property can be a simple variable or a structure.

This is my class:

classdef myClass <   dynamicprops

methods
    function obj = myClass()

          NewProp = 'myProp';
          DynamicProp=addprop(obj,NewProp);
          DynamicProp.SetAccess='public';
          DynamicProp.GetAccess='public';

          DynamicProp.SetObservable=true;
          DynamicProp.GetObservable=true;
          addlistener(obj , NewProp , 'PreGet' ,  @obj.PreReadProperty);
          %addlistener(obj , NewProp , 'PreSet' , @obj.PreSendProperty);
          addlistener(obj , NewProp , 'PostGet' ,  @obj.PostReadProperty);
          %addlistener(obj , NewProp , 'PostSet' , @obj.PostSendProperty);
      end
      function PreReadProperty(obj,  inputMetaProp, varargin)

          DynamicProp=obj.findprop((inputMetaProp.Name));
          disp(obj.(DynamicProp.Name))
          %Body
      end
      %
      function  PostReadProperty(obj,  inputMetaProp, varargin)
          %DynamicProp=obj.findprop(inputMetaProp.Name);
          % Body
      end

end
end

I am trying to catch in a PreReadProperty the value that I access before displaying it.

Example:

>> myVar = myClass;
myVar.myProp = 1;
mytest = myVar.myProp;
     1

>> mytest

mytest =

       1
This works fine for a variable. I can catch it and work with it

I am trying to do the same thing when myVar.myProp is a structure:

>> myVar = myClass;
>> myVar.myProp.myProp1 = 1;
>> myVar.myProp.myProp2 = 2;
    myProp1: 1

>> mytest = myVar.myProp.myProp1;
    myProp1: 1
    myProp2: 2
>> mytest

mytest =

       1
This doesn't work as expected. I tried to browse inputMetaPropand varargin but I still cant get my read value in the PreReadProperty function

When I read myVar.myProp.myProp1 I want to catch its value in PreReadProperty. Is there any way to do this?

Regards

Answer 1

[Adam]

You would need something more like:

addlistener(obj.NewProp, 'myProp1', 'PreGet' ,  @obj.PreReadProperty);

to listen to the actual property that is being set rather than the structure property that contains it. But in your situation that doesn't make sense since you are dealing with a dynamic property and your class does not know about the existence of 'myProp1'.

If you can move away from dynamic properties to static properties then you could do this, but otherwise what you are effectively trying to do is have your class listen for a change to a property it doesn't even know exists.

[Florin]

Hello,

Unfortunately this doesn't work in my case. I need to use dynamic properties and the structure tree does not stop at 1...2

Listening for a change is not so difficult. Listening for a call is. I am trying to catch my value while executing the 'PreReadProperty' function.

In debug mode (somewhere in 'PreReadProperty' function) if I use twice 'dbup' (go to Base) I get the correct value in the variable 'ans'

Regards