OGNL has a simple variable scheme, which lets you store intermediate results and use them again, or just name things to make an expression easier to understand. All variables in OGNL are global to the entire expression. You refer to a variable using a number sign in front of its name, like this:
OGNL also stores the current object at every point in the evaluation of an expression in the this variable, where it can be referred to like any other variable. For example, the following expression operates on the number of listeners, returning twice the number if it is more than 100, or 20 more than the number otherwise:
listeners.size().(#this > 100? 2*#this : 20+#this)
OGNL can be invoked with a map that defines initial values for variables. The standard way of invoking OGNL defines the variables root (which holds the initial, or root, object), and context (which holds the Map of variables itself).
To assign a value to a variable explicitly, simply write an assignment statement with a variable reference on the left-hand side:
