Function to create struct with parameters

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Currently I have a function with settings/parameters for my program, where all parameters are written into a struct like "inp.month = 7;" so that I can pass the struct "inp" to functions afterwards. Is it possible to have all the assignments in the function without the struct, eg "month = 7;" and at the end somehow get 'all variables in this function' into the struct "inp". Something like "inp = <gather all variables assigned in this function>", and then have the struct be the output. It would add readability in my opinion and also I thought this to be easy, but didn't find a good solution yet and thought I'd ask here.
Cheers
Felix
  5 Comments
Bruno Luong
Bruno Luong on 27 Apr 2021
This request is interesting only for lazy programmers who wants to make a quick and dirty code.
Just create a struct with the list of variables that you control explicitly.
Felix Müller
Felix Müller on 27 Apr 2021
Well, that might not be so obvious before thinking about it, eh?

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Accepted Answer

Jeff Miller
Jeff Miller on 26 Apr 2021
Maybe you would like something like this?
month = 1;
year = 1951;
day = 11;
inp = CreateStruct(month,day,year)
function outstruc = CreateStruct(varargin)
% Create a structure with the input variables as fields.
outstruc = struct;
for iField=1:numel(varargin)
sfName = inputname(iField);
outstruc.(sfName) = varargin{iField};
end
end
  2 Comments
Felix Müller
Felix Müller on 27 Apr 2021
Thanks, that does look interesting. Do you think there are any drawbacks or weird errors that could pop up while using this?
Stephen23
Stephen23 on 27 Apr 2021
Edited: Stephen23 on 27 Apr 2021
"Do you think there are any drawbacks...?"
Slower code: "Avoid functions that query the state of MATLAB such as inputname, which, whos, exist(var), and dbstack. Run-time introspection is computationally expensive."

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More Answers (2)

Walter Roberson
Walter Roberson on 26 Apr 2021
The following code is not recommended.. but it should work.
ZZ_filename = [tempname '.mat'];
save(ZZ_filename, '-struct', '-regexp', '^[^Z]', '^Z[^Z]');
inp = load(ZZ_filename);
delete(ZZ_filename);
If you already have variable names that begin with 'ZZ' then this code would have to be modified.
The purpose of the -regexp is to allow saving all of the variables except the over-head variable ZZ_filename .
  3 Comments
Walter Roberson
Walter Roberson on 26 Apr 2021
Then you will need to write code that uses dynamic variable naming, which is not at all recommended.
Hint: who() returns names of variables.
Felix Müller
Felix Müller on 26 Apr 2021
Okay, thanks! I thought it might work without fiddling with the assignment of variables myself (eg with a function written exactly for this), but it might not.

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Bruno Luong
Bruno Luong on 27 Apr 2021
s = buildparams()
s = struct with fields:
a: 1 b: 2
function s = buildparams()
a = 1;
b = 2;
s = gathervars();
end
function s = gathervars()
vars = evalin('caller', 'whos');
for k=1:length(vars)
name = vars(k).name;
s.(name) = evalin('caller', name);
end
end

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