Avoiding eval in symbolic to function

I use the symbolic toolbox in matlab to generate some very long symbolic expressions. Then I use matlabFunction to generate a function file. Say there are three parameters: p1, p2 and p3. I have a cell with strings {'p1', 'p2', 'p3'}. In the derivation of the model I generate symbolic variables p1, p2 and p3 out of them using eval in a loop and stack them in a vector par. Then when in matlabFunction, I specify par as input. Moreover, I save the cell string in a .mat file.

Then when I want to simulate this model, I can construct this parameter array using that cell of strings from the .mat file out of 30 available parameters and their values.

Advantages: No need to keep track of the different parameters if I add one to . I can change the order, mess around, but older models still work. Disadvantage: Turning things into a function file leads to this error (psi is one of the parameters):

Error: File: f_derive_model.m Line: 96 Column: 5 "psi" previously appeared to be used as a function or command, conflicting with its use here as the name of a variable. A possible cause of this error is that you forgot to initialize the variable, or you have initialized it implicitly using load or eval.

Apparently some unnescescary checking is going on because the variable will be intialized in an eval statement.

*Question: How can I avoid eval but keep the list of parameters indepent from the model stuff.*

Code deriving the long equations:

    % Model parameters
    mdl.parameters = {'mp','mb','lp','lb','g','d','mP','mM','k','kt'};

    par = [];
    for i=1:length(mdl.parameters)
        eval(strcat(mdl.parameters{i}, '=sym(''', mdl.parameters{i}, "');"));
        eval(sprintf(['par = [par;' mdl.parameters{i} '];']));
        end

    %%Calculate stuff

    matlabFunction(MM,'file',[modelName '_mass'],'vars',{par},'outputs',{'M'});

Code using the generated file:

        getparams
        load('m3d_1')

        par = [];
        for i=1:length(mdl.parameters)
            eval(sprintf(['par = [par;params.' mdl.parameters{i} '];']));
        end

See how, as long as I specify the correct value to for example params.mp, it always gets assigned to the input corresponding to the symbolic variable mp in the par vector. I do not want to lose that and have to keep track of the order and so on, nor do I want to call my functions with all the parameters one by one.