How to use variables in a subsystem mask

Hi!

I am working on a subsystem mask that changes its outputs depending on a popup. The thing is that I have to know which was the previous popup item selected to do one change or another.

I am doing it by using one parameter of the mask. It works when it is shown in the mask ( show parameter checked), but when I hide it (I don't want to see this variable) it stop working properly.

Is there any way to use variables instead of parameters to do that?

Many thanks!

[Kaustubha Govind]

How does the user change the pop-up value if it is invisible?

[Dani Tormo]

There is the pop-up and the parameter working as a variable. The pop-up can be changed by the user but not the variable (which is changed by the pop-up callback). The variable is blocked for the user.

[Kaustubha Govind]

Dani: Are you saying that the hidden parameter stores the previous value of the visible popup parameter? If so, how do you access the previous value from the dialog callback?

[Dani Tormo]

Yes. When I change the pop-up value, it reads which was the previous pop-up value stored in the hidden parameter/variable. Then it executes the proper modifications and then updates the hidden parameter/variable with the actual pop-up value to be ready for the next change (if any).

[Kaustubha Govind]

How do you read the previous value exactly? I thought that get_param returns the new value when called from the parameter callback?

[Dani Tormo]

Yes, it returns the new value, when I need to know the previous one. For this reason I need to use another parameter to store which was the previous pop-up value and at the end of the callback I store the new value. The parameter where I store the previous value shouldn't be modifiable by the mask. This is the code by the way, topology is the pop-up parameter and previous_topology is where I save the previous pop-up value:

 % Pop-up callback

 previous_topology = get_param(gcb,'previous_topology');

 if strcmp(get_param(gcb,'topology'),'Num. 1')

    switch previous_topology
        case '2'
            % Execute changes when coming from Topology 2...

        case '3'
            % Execute changes when coming from Topology 3...

    end

    set_param(gcb,'previous_topology','1');

 elseif strcmp(get_param(gcb,'topology'),'Num. 2')

    switch previous_topology
        case '1'
            % Execute changes when coming from Topology 1...

        case '3'
            % Execute changes when coming from Topology 3...

    end

    set_param(gcb,'previous_topology','2');

 elseif strcmp(get_param(gcb,'topology'),'Num. 3')

    switch previous_topology
        case '1'
            % Execute changes when coming from Topology 1...  

        case '2'
            % Execute changes when coming from Topology 2...

    end

    set_param(gcb,'previous_topology','3');

 end

[Dani Tormo]

Is going to help me someone? I still having problems with the use of this parameter as a variable.

Many thanks!

[Zoe Xiao]

I tried your code in 2017a, and it worked fine if you deselect the 'visible' check box of the mask parameter.