Using a value of a struct from workspace in a script based on its name

Question

I'm working on a project and I need to work with certain variables from the workspace and I only have their name as a char array.

To make an example, I have array

var_names = {'var1', 'var2', ... }

and these variables are (among many others) in the workspace as structs with multiple attributes - value, class etc. (I believe these are Simulink generated but I am not absolutely certain).

To simplify, say I have the names {'var1', 'var2'} and I need to make a product of their values

prod = var1.Value * var2.Value

I tried things like

var_names(1).Value * var_names(2).Value

and similar more obvious attempts but none were successful. A note - the eval doesn't work because of the struct nature of the variables and I need something else.

If you can sort all variables in a master structure, you can access the variables like this: masterStruct.(var_names{1}). This is much faster than eval. — Anthony
– Anthony, Commented Jul 21, 2018 at 8:52
I used eval similarly as in your answer, Mad Physicist. I can't remember the exact use but the problem is it doesn't work with Simulink.Parameter. The strange thing is that the code I wrote works in another script I wrote to test it but when I copy the exact same code into the large function I'm working on fixing, it stops working, saying Error using eval, Undefined function or variable 'Nameofvar'. Also, for some reason, if I change the value of said variable manually, it works for the one var and then breaks at the next one. — user145760
– user145760, Commented Jul 23, 2018 at 9:06
If you could show a sample of the misbehaving code, we'd be able to help you. — Mad Physicist
– Mad Physicist, Commented Jul 23, 2018 at 12:27

Mad Physicist · Accepted Answer · 2018-07-21 07:54:22Z

2

The standard way to get a variable by name is using eval. The important thing is to make sure to evaluate the right text:

names = {'var1', 'var2'};
x1 = eval(names{1});
x2 = eval(names{2});
prod = x1.Value * x2.Value

edited Jul 21, 2018 at 7:54

answered Jul 21, 2018 at 7:47

Mad Physicist

116k29 gold badges202 silver badges292 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Using a value of a struct from workspace in a script based on its name

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related