evalin data dictionary design data unable to use parameters on rhs of expression

Question

Adam Jaslikowski 2020-8-25

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评论： Adam Jaslikowski 2020-8-28

I'm trying to write a MATLAB script that can perform pre-processing computations on a data dictionary prior to Simulink running. I've been trying to write a script that is called from the 'evalin' interface with the Dictionary design data section as the first input and my script as the second:

evalin(section,'my_script');

Assume the dictionary already has parameters x and y with some arbitry values

if my_script.m has:

x=1;
y=2;

There's no problem. If I modify my_script.m to:

y=x+1;

There is an error when calling evalin:

"Could not evaluate 'my_script' in data dictionary

Caused by:

Error occurred."

After further testing, it doesn't seem like I can use an existing parameter anywhere on the rhs of an equation. Is this correct?

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Answer 1

Mohith Kulkarni 2020-8-28

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The "evalin" function for data dictionary section does not support the expressions where the value contains data entries as of now. But I have brought this issue to the concerned people and it might be considered in any future release.

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Adam Jaslikowski 2020-8-28

Thank you

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Answer 2

stozaki 2020-8-28

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编辑：stozaki 2020-8-28

The "evalin" function for data dictionary section does not support the expressions.

The workaround can be replaced by the following formula.

Simulink.data.evalinGlobal(modenName,expression)

Simulink.data.evalinGlobal

For example, how about preparing a wrapper function like the following?

function [Object] = evalinCustomWrap (modelName,varStr)
modelVar = verLessThan('Simulink','8.5');
if ~modelVar
    % If the target model is using a MATLAB release supported by .sldd
    try
        Object = Simulink.data.evalinGlobal(modelName,varStr);
    catch
        Object = [];
    end
else
    % If the target is using a MATLAB release that does not support sldd
    % Only evalin can be used
    try
        Object = evalin('base',varStr);
    catch
        Object = [];
    end
end
end

Regards,

stozaki

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Adam Jaslikowski 2020-8-28

I'm experiencing the same issue when attempting to use Simulink.data.evalinGlobal. This is very dissappointing. I just learned of data dictionaries and they seem like very useful tools; however, my use case requires a great deal of pre-processing on the data prior to use by the Simulink model and it seems like that is just not supported (other than doing a lot of calls to "getEntry" and "getValue"). Thank you for trying to help,

Adam

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