Mad Map Mocking

1. Closures

   Closure addToY = { x -> x+y; } defines a closure

   • A method with argument "x" , returning the sum of x and y.
   • It's also an object.
   • Like anonymous inner classes, but somehow easier.
   • Lexically scoped: y is defined outside the closure.

   Closures can have any number of arguments (optionally typed) and any number of statements.
2. Maps (syntactic sugar)

   Map map = [ "x" : 7, "y" : "foo" ]
   is equivalent to:

   Map map = new LinkedHashMap(2);
   map.put("x", 7);
   map.put("y", "foo");
   

   Map map = [ x : 7, y : "foo" ] means the same thing. (Parentheses are required if the key is not a string.)

3. Maps members can be accessed like properties or methods
   (from the interactive program "groovysh")

   groovy:000> Map m = [ f : { x -> x+1 } ]; m.f(3);
   ===> 4
   

4. Lying to the type system.

   HttpServletRequest r = [ getAttribute : { x -> "whatevaah" } ] as HttpServletRequest