How to use macros to automatically create matcher for case classes

1. Vampire Methods
ScalaSyd

2. Can you do this?

3. @xeno_by jumps in

4. Kittens!

5. Kittens!
Generate a local class!

6. Local CatMatcher

7. Paradise plugin
Just for quasi-quotes

8. Local CatMatcher

9. Batman

10. Local CatMatcher
http://stackoverflow.com/questions/18480707/method-cannot-
be-accessed-in-macro-generated-class
Don’t forget the {}!

11. Real incremental recompilation

12. Let’s dive

13. Grab the Cat
TypeTag not accessible in a macro!

14. Wash the Cat

15. Inception matcher
Builder pattern
Matcher methods
// CatMatcher

16. Inception matcher
Cat matcher
Internal state

17. Inception matcher
new constraint =>
new matcher function
name/age/kitten methods
list of c.Expr[_]

18. Mirror, mirror
structural type =>
reflection :-(
// age
// matchA[Cat].age(6)
// Int

19. Yo, I heard you like macros
No structural type!

20. Yo, I heard you like macros
Annotation code
// @fieldMatcherBody(expected => cat.age must_== expected)
// val expected = 6
// cat.age must_== expected

21. Yo, I heard you like macros
extract parameter/body

22. Transformers
// 6
// `prefix` represents an equivalent of
// `this` for normal instance methods
// body:
// CatMatcher.this.addMatcher((_:Cat).age must_== arg)

23. Transformers
http://stackoverflow.com/questions/18523871/use-this-in-a-
generated-macro-method

24. Transformers -Yrangepos

25. Can you do this?
YES !!!

26. Thank you!
If you followed that far…