Power Groovy DSL Features
[ 176 ]Running the preceding code will output the following text:
Class method this is : class Clazz
Closure this is : class ConsoleScript1
Closure Closure this is : class ConsoleScript1
Method Closure this is : class Clazz
Script this is : class ConsoleScript1
So, the rules for resolving this, owner, and delegate in the various contexts are:
- In a class instance method, this is always the instance object. owner and
delegate are not applicable and will be disallowed by the compiler - In a class static method, this, owner, and delegate references will be
disallowed by the compiler - In a closure defined within a script, this, owner, and delegate all refer to
the Script object unless delegate has been reassigned - In a closure within a method, this and owner refer to the instance object
of the enclosing class; as will delegate, unless it has been reassigned to
another object - In a script, this is the Script object, and owner and delegate are
not applicable
How builders work
Earlier, when we looked at the MarkupBuilder code, the unfamiliar syntax must
have seemed strange. Now that we have an understanding of how the MOP and
pretended methods work, let's take a quick look again at some builder code and see
if we can figure out what might be happening. MarkupBuilder is derived from the
BuilderSupport class. When describing how MarkupBuilder works, I won't make a
distinction between BuilderSupport and MarkupBuilder. Most of the mechanisms
described here are in fact implemented by BuilderSupport and are shared with
other Builder classes:
def customers = builder.customers {
customer(id:1001) {
name(firstName:"Fred",surname:"Flintstone")
address(street:"1 Rock Road",city:"Bedrock")
}
customer(id:1002) {
name(firstName:"Barney",surname:"Rubble")
address(street:"2 Rock Road",city:"Bedrock")
}
}http://www.ebook3000.com