Code generation can be used to generate boilerplate code from models but requires manual coding to add behavior. Protected regions allow regenerating while preserving manual changes but not all tools support it. The "generation gap" pattern separates generated structure code from manual behavior code, but behavior is still written manually. Model-driven development with a general-purpose modeling language (GPL) like UML and full code generation from models could solve this by making models the central artifacts that are precise, complete and executable.

1. Code generation: Going all the way Rafael Chaves [email_address] http://alphasimple.com

2. Defining "code generation"

4. Step 1: basic code generation from models

6. package banking; public class Account { private Double balance; public Double getBalance() { return this.balance; } public void setBalance(Double balance) { assert balance != null; this.balance = balance; } public void deposit(Double amount) { /* FILL ME IN */ } public void withdraw(Double amount) { /* FILL ME IN */ } }

8. Step 2: using protected regions

9. package banking; public class Account { private Double balance; public Double getBalance() { return this.balance; } public void setBalance(Double balance) { assert balance != null; this.balance = balance; } public void deposit(Double amount) { //BEGIN-USER-CODE this.balance = this.balance + amount; //END-USER-CODE } ... }

11. Step 3: applying the Generation Gap pattern

12. Source: IBM Research

13. // GENERATED - DO NOT MODIFY package banking; public class AccountCore { protected Double balance; public Double getBalance() { return this.balance; } public void setBalance(Double balance) { assert balance != null; this.balance = balance; } public void deposit(Double amount) { // override me } public void withdraw(Double amount) { // override me } }

14. package banking; public class Account extends AccountCore { public void deposit(Double amount) { this.balance = this.balance + amount; } public void withdraw(Double amount) { this.balance = this.balance - amount; } }

16. What problem are we trying to solve again?

17. Enterprise software is much harder than it should be Problem domains are typically not very complex (information management + business rules) How come? Secondary concerns abound persistence, concurrency, (a)synchronism, distribution, transactions, security, caching, replication, logging, ...

19. Problem hypothesis: lack of separation between technical and domain concerns is the root of all evil

20. Solutions Using ordinary 3GL + reflection/AOP Model-driven development with DSLs Model-driven development with a GPL (like UML)

23. Solution hypothesis: Model-driven development with a GPL and full code generation

26. Demo: Executable modeling and full code generation with AlphaSimple

27. Validating hypotheses

29. Model-driven development is not about taking work (or fun) away from developers, but making their work more meaningful and valuable

30. Code generation: Going all the way Rafael Chaves [email_address] http://alphasimple.com