MATLAB: Copying option structs by value instead of reference

MATLABprogramming

Here is an example using bodeoptions, but this is probably a much more basic problem:
% Create a struct with default values
opt1 = bodeoptions;
% Change a value
opt1.MagScale = 'log'
% Now generate another (?) struct with the same options
opt2 = opt1;
% Change the value in the original struct back to default
opt1.MagScale = 'linear'
% Surprise! The value is changed back in the 'copy,' too
opt2.Magscale
Similarly, changing anything in opt2 changes opt1, too, so it appears opt2 is not another struct but a reference to the same structure as opt1.
Can anybody tell me what's happening here, and in particular: How would I create a copy of opt1 that I can change without changing opt1, too?

Best Answer

Most likely, bodeoptions returns a handle class rather than a structure.
   whos opt1
would tell you.
Matlab does not have a built-in way to do deep copy of handle classes. Possibly, the class has a method to do this. You can check with
   methods(opt1)
But in any case, what's stopping you from creating your second variable with:
opt2 = bodeoptions;
It'll start out the same as opt1 but will be a different object.
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