Variable assignment in function calls

Genero BDL behaves differently to I4GL when variables are changed in expressions evaluated in function parameters.

When calling a function with expressions as parameters, these expressions must be evaluated before calling the function. If an expression changes a program variable that is also used as function parameter, IBM® Informix® 4GL pushes the evaluated values sequentially on the stack, while Genero BDL first evaluates all parameters, then pushes the list of values on the stack.

To illustrate this difference, see the following example:

DEFINE gv INT

MAIN
    LET gv = 1
    CALL func(gv, add(), gv)
END MAIN

FUNCTION add()
    LET gv = gv + 1
    RETURN gv
END FUNCTION

FUNCTION func(p1,p2,p3)
    DEFINE p1,p2,p3 INT
    DISPLAY p1,p2,p3
END FUNCTION

Result with I4GL:

          1          2          2

Result with BDL:

          2          2          2

The behavior of Genero BDL is better than I4GL, using a consistent value of the modified variables, for all parameters passed to the function.

Replace the above code by:

MAIN
    LET gv = 1
    LET gv = add()
    CALL func(gv, gv, gv)
END MAIN