How do I use a Variables to Call a Function?

How do I use a Variables to Call a Function?

Hello. I'm working on a Zoho App where I will be using many functions for determine eligibility for client membership and each function's name will be assigned to a specific Criteria form. The Criteria form will have a String or Text field named "Function Name". 

I'm hoping to call the function name on a separate Form named "Screening" where if the Criteria Type is equal to "Function" and the "Function Name" is present, it will use that particular function assigned variable to call the specific function to run.  Is this possible to do as my initial attempts have not been successful as it states:

"Error at lineNumber:1 Function:thisapp.calculations. EC.Function_Name() does not exist"

I hope to do this rather than create If statements for every function that I'll be creating - as they can number more than 100 when I'm done.

Here's the value expression that I'm trying to use where "EC.Function_Name" is the lookup field name:

input.Resp = thisapp.calculations.EC.Function_Name(input.Client_ID, input.Eligibility_Criteria_Name)

This is the original script: where the EC.Function_Name is supposed to be function "Age"

for each EC in Eligibility_Criteria  [Eligibility_Criteria_Name == input.Eligibility_Criteria_Name]
{
    Criteria_Type:ui.add(EC.Criteria_Type);
    Criteria_Type.select(EC.Criteria_Type);
    Resp:ui.add(EC.Positive_Outcome);
    Resp:ui.add(EC.Negative_Outcome);
    Resp:ui.add(EC.Possible_Outcome);
    if (EC.Function_Name  !=  "")
    {
        input.Resp = thisapp.calculations.Age(input.Client_ID, input.Eligibility_Criteria_Name);
    }
}

If there is a better way to accomplish this please let me know.

Thanks.