Every developer dreams about big red button to do everything he needs. MOP (Metaobject protocol) in Groovy is a way to get close to that dream. There is a presentation of meta programming concepts in Groovy and what benefits you can get from it.

1. Groovy
MOPping
Izzet Mustafayev@EPAM Systems
@webdizz
http://webdizz.name

2. this is me
● SA at EPAM Systems
● primary skill Java
● hands-on-coding with Ruby, Groovy, some
Scala
● passion about agile, clean code practices
and devops

3. agenda
● Groovy
● MOP... what?
● AOP
● method injection/synthesis
● AST
● summary
● q&a

5. Groovy

6. Groovy is an agile dynamic language

7. Java is a Groovy but Groovy is not Java

8. Groovy supports DSL

9. Groovy provides statically type check

10. MOP...?

11. MOP Example GORM
class Person {
String name
Integer age
Date lastVisit
}
​
Person.findByName('Jack')

12. Groovy Object
package groovy.lang;
public interface GroovyObject {
Object invokeMethod(String name, Object
args);
Object getProperty(String property);
void setProperty(String property, Object
newValue);
MetaClass getMetaClass();
void setMetaClass(MetaClass metaClass);
}

13. Object operation
str = 'hello'
method = str.metaClass.getMetaMethod
('toUpperCase')
​
println method.invoke(str) // HELLO

14. AOP

15. groovy.lang.GroovyInterceptable#invokeMethod

16. groovy.lang.MetaClass#invokeMethod

17. method injection

18. Category

19. ExpandoMetaClass

20. Class Instance

21. Mixing

22. method synthesis

23. methodMissing()

24. ExpandoMetaClass

25. AST transformations

26. interception

27. injection

28. summary

29. DSL

30. Source Analysis

31. Dependency Management

32. references
● Groovy http://groovy.codehaus.org/
● CodeNarc http://codenarc.sourceforge.net/
● Gradle http://www.gradle.org/
● Gant http://gant.codehaus.org/
● Writting DSL http://groovy.codehaus.org/Writing+DomainSpecific+Languages
● Dynamic Groovy http://groovy.codehaus.
org/Dynamic+Groovy
● Demo sources https://github.com/webdizz/groovy-mopping

33. q&a

34. thank you!
Groovy
MOPping
Izzet Mustafayev@EPAM Systems
@webdizz
http://webdizz.name