combobox perfoming different formulas based on user selection

Question

I have a datagrid where users put in different numbers for 3 different columns. These values are then calculated after the user puts in each value for each column. I also have a combobox component inside my datagrid. What I want this combobox to do is perform a different mathematical formula based on what the user selects. For example, in the combobox if the user selects 'Long'(the first option in the combobox) it performs Column1*(col2-Col3)-col4=total column or if the user selects 'Short'(the second option in the combobox) it performs col1*(Col3-col2)+column4=total column. How would I do that? I've tried different ideas none which have seemed to work so any examples or suggestions would be greatly appreciated.

   public function getTotal(item:Object, column:DataGridColumn):String
    {
    switch(comboBox) 
        { 
            case "Long": 
                var sum:int = item.quantity*(item.exit-item.entry)-item.commission;
            return currencyFormatter.format(sum);


            case "Short": 
                sum = item.quantity*(item.entry-item.exit)-item.commission; 
            return currencyFormatter.format(sum);


        }

    }

Answer 1

Your question is a bit confusing. How can a user "put in different values" that "are then calculated" Users do not usually input calculated values!

That said, it sounds like you need a big switch statement to calculate the values.

switch(comboBox.selectedItem) 
{ 
    case ""ong": 
        calculatedValue = Column1*(col2-Col3)-col4; 
        break; 
    case "Short": 
        calculatedValue = col1*(Col3-col2)+column4; 
        break; 
}

I assume all the values displayed in your DataGrid relate to a specific object created for that row. You can put your calculate function in the renderer for your caluclated column and reference those items of your object's dataProvider directly:

switch(data['comboBoxSelectedItem']) 
{ 
    case ""ong": 
        data['calculatedValue'] = data['Column1Value']*(data['col2Value']-data['Col3Value'])-data['col4Value']; 
        break; 
    case "Short": 
        data['calculatedValue'] = data['col1Value']*(data['Col3Value']-data['col2Value'])+data['column4Value']; 
        break; 
}

Answer 2

I took the idea that you gave me and used parameters for the function but like I said before I keep running into error 1170. I get that it is saying my function is not returning a value but I dont understand why? Any clarification is more than welcome.