Generalizing Function Calls with Property Dependence in App Designer

I have code that is formatted like below in App Designer. Properties I1, I2, and I3 are all callable from an instrument with their own method. So far I've just been repeating the same code in each button push callback, but I want to write a general function instead so I don't repeat code. The example below is a simple one for this purpose, but you could imagine how convoluted it could get for several methods. I understand why the code below doesn't work (it's calling a string, not the property). I am unclear as to how to generalize a format of a property and call it in the function. Help is appreciated.

Version 2020b. An upgrade is possible, if that assists with the solution.

%this is the start of App Designer 
properties (Access = private)
    I1
    I2
    I3
end 
    
methods (Access = private)

function change_current(app, unit_number)
    prop_name = join(["I", unit], '')  
    app.prop_name.current(40) %the code errors here as it should, since it's calling a string and not the property...how to do?
end

end

Answer 1

[chicken vector]

Use:

app.(prop_name).current

to use strings as class properties (or structure fields).

[etia]

Thank you, this worked!