Why is MATLAB code excution in a function not in a sequence like in the main script?

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Yi Wan
Yi Wan 2018-10-22
评论： Walter Roberson 2018-10-22
So here is the example:
% I run the initparameter file first
% the file contains a rigidbodytree object called robot
% Then define results = robot, it works fine
run('InitParameters.m');
results=robot;
% However, if I put this into a function
% The 'initparameter' file is not excuted first.
% This gives me an error indicating that robot is not found.
% The 'initparameter' file is not executed at all.
result=myfun();
function results=myfun()
run('InitParameters.m');
results=robot;
end
So is there a way to have the code run in sequence in a function just like in the main script? Maybe there is a duplicate to this question, but I can't seem to describe this properly... Please excuse me.
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Yi Wan
Yi Wan 2018-10-22
@Kevin, Unfortunately, the same error still occurs.
However, you mentioned 'interaction' which enlightened me. I tried inserting a break point at 'result=robot'. The first line (InitParameter) does execute. However, as soon as I jump to the second line, all the 'base' workspace variables are cleared. So I think it's more of a function scope problem.
That may be also why when the two lines are excuted in the global scope, it doesn't have that issue.
I'll try again with some other methods. Thanks for the advice anyway!

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Walter Roberson
Walter Roberson 2018-10-22
run() is a function that determines which file is being invoked and then does an evalin('caller') of the file.
When the script being executed is executed from the command line, the 'caller' will be the base workspace, and any assignin('base') that are executed will result in variables that are directly available to the calling environment because the calling environment is also the base workspace.
When the script being executed is executed from a function, the 'caller' will be the function that run was called from, and any assignin('base') that are executed would result in variables that are in the base workspace but not in the workspace of the function.
The easiest fix for this direct issue would be
function results=myfun()
InitParameters;
results = evalin('base', 'robot');
end
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Walter Roberson
Walter Roberson 2018-10-22
Run does itself deliberately assign values in the base workspace, but the script being executed might.

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