How to access struct member via a string
6 views (last 30 days)
Show older comments
Let's say I create a struct via the following:
airplane.cockpit.controls.throttle = 'forward'
I can access those fields like this:
airplane.('cockpit').('controls')
Is it possible to use these semantics but with a string representation? I've tried this:
s = "('cockpit').('controls')"
airplane.(s)
Reason for asking is that I have a configuration file that use the same structure notation to "drill" down into the structure. I'd like to be able to read that configuration file to access certain members of the struct
1 Comment
Stephen23
on 5 Oct 2023
Edited: Stephen23
on 5 Oct 2023
"Is it possible to use these semantics but with a string representation?"
Not easily. But you can easily use SPLIT and GETFIELD.
An explanation of why your approach does not work: https://www.mathworks.com/matlabcentral/answers/1656435-tutorial-comma-separated-lists-and-how-to-use-them#answer_966455
Accepted Answer
Matt J
on 5 Oct 2023
Edited: Matt J
on 5 Oct 2023
Here is something simiilar:
airplane.cockpit.controls.throttle = 'forward';
s={'cockpit','controls'};
getfield(airplane,s{:})
2 Comments
Fangjun Jiang
on 5 Oct 2023
airplane.cockpit.controls.throttle = 'forward';
s = "('cockpit').('controls')";
pth=extractBetween(s,"'","'");
getfield(airplane,pth{:})
More Answers (1)
Bruno Luong
on 5 Oct 2023
Edited: Bruno Luong
on 6 Oct 2023
I made this for my own use. It is not a dot syntax, just the functional form.
The constraint is that accessing nested subfield(s) should be scalar.
Assignment automatically creates the intermediates nested structures if they do not exist.
Error handling when retreive if the intermediate/final nested structures do not exist.
airplane = struct()
airplane = rsetfield(airplane, 'cockpit.controls.throttle' , 'forward')
airplane.cockpit.controls.throttle
[value success] = rgetfield(airplane, 'cockpit.controls.throttle')
[value success] = rgetfield(airplane, 'cockpit.controls.alarm')
0 Comments
See Also
Categories
Find more on Structures in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!