@Hamlet: I figured this out in sort of a similar way myself. One day I was messing around with the metaclass and had it list all of the metaMethods on a custom class that I had.

class Foo {}
 
println new Foo().metaClass.metaMethods*.name.unique().sort()
 
/* prints 
 
["addShutdownHook", "any", "asType", "collect", "dump", 
"each", "eachWithIndex", "every", "find", "findAll", 
"findIndexOf", "findIndexValues", "findLastIndexOf", "getAt",
"getMetaClass", "getMetaPropertyValues", "getProperties",
"grep", "identity", "inject", "inspect", "invokeMethod", "is", 
"isCase", "iterator", "print", "printf", "println", "putAt", 
"sleep", "sprintf", "use", "with"]
*/

I saw that all of the iteration methods were already on there. After an initial “WTF?” and some digging into the groovy source, I figured out what was going on.

I eventually found DefaultGroovyMethods which is a goldmine of groovy treasures. It’s also by far the largest class in the groovy source tree (~10,300 lines of code!). Almost all of the whizzy stuff that you get without doing an import originates in that file.

After learning this, my code started to look very, very loopy because you can define algorithms that work across data structures treating everything as a List… if an algorithm encounters a non-list then the each() method never iterates without throwing an exception. Nice stuff.