Error Messages/40616

Error message examples

You cannot assign to a slice or subscript of a global variable object.

Cause

You may not assign a value to a slice (subscripted element) of a global variable.

You may assign to a slice of a local variable. And in a Script or Function called from the Script of a Button or other object, you may assign a new value to a global variable (but not a slice of it.)

This example triggers this error. Here BadDef tries to assign to a slice of the global variable X:

 Index I := 1..9
 Variable X := Table(I)(7, 8, 3, 2, 5, 4, 9, 1, 5)
 Variable BadDef := (X[I = 5] := 99)

Remedies

If you want to assign to a slice of a global variable from a Script or a User-Defined Function called from a Script, you can do so indirectly. It's usually simplest to write the code in a user-defined Function called from a Script, rather than directly in a Script. In a Function F:

1. copy the global array, X, into a local variable, local_x,
2. assign a new value to a slice of local_x,
3. assign the value of local_x back to the global, X,
4. finally, call function F from a Button script.

For example, suppose you want to assign 999 to the 5th element over index I of global variable X:

   Function Assign_to_X(v)
     Definition: 
        Variable local_x := X;
        local_x[I =5] := v;
        X := local_x

   Button Do_Assign
     Script:  Assign_to_X(999)

When you press the button, Do_Assign, it calls Assign_to_X(999) and completes the slice assignment.

See Also

• User-Defined Function
• Local Variables
• Assignment Operator :=
• Slice
• Subscript
• Script
• Button