This document discusses using aspects for language portability. It introduces four classes of portability aspects: 1) glue code aspects, 2) migration aspects, 3) integration aspects, and 4) optimization aspects. These aspects address additional portability issues beyond just replacing the backend, such as platform-specific libraries, unportable code, platform integration, and performance. Aspect-oriented programming is proposed as an elegant way to encapsulate platform-specific concerns in separate libraries.

1. Using Aspects for
Language
Portability
Lennart Kats Eelco Visser

3. DSLs
Stratego
SDF
Spoofax

4. DSL compilers
(code generators)
DSL Generator

5. Backend targets the
platform
DSL Frontend Backend

6. Backend targets the
platforms
DSL Frontend Backend
Backend
Backend

7. “So switching to another
platform is just a little
matter of switching the
backend, right?”
(wrong)

8. Why not?
• platform-exclusive libraries
• platform escapes and native calls
• interoperability and integration with
platform applications
• performance and stack behavior

9. Then what?
Use aspect weaving to address portability
issues in programs and libraries!

10. Our case study
Frontend Backend C/POSIX
Stratego/XT

11. Our case study
Frontend Backend C/POSIX
Stratego/XT
Backend

12. Why Java?
(spoofax.org)

13. Architecture
Frontend
Backend

14. Architecture
Frontend Standard libs
Backend Programs

15. Architecture
Frontend Standard libs Primitives
Backend Programs Platform libs

16. Architecture
Frontend Standard libs Primitives
Backend Programs Platform libs

17. Architecture
Frontend Standard libs Primitives
Backend Programs Platform libs
Portability
aspects

18. 1. Glue code aspects
Override functions and library invocations
to work with platform-specific libraries
• SGLR vs. JSGLR
• ORM
• communication
• etc.

19. 2. Migration aspects
Because we cannot solve all portability
problems (right away)
• There may be no alternative for a library
• Primitives may make assumptions about
the platform (e.g., POSIX vs. Java)

20. 2. Migration aspects
Warn developers about unportable code
Perform “next best” operation

21. 3. Integration aspects
Enhance platform integration:
• error handling (exceptions, console vs. GUI)
• logging
• hooks
• user interaction (console vs. GUI vs. web)

22. 4. Optimization aspects
Address platform performance issues of...
...expensive operations
...common operations (bottlenecks)
by using platform-specific code
or by using code more suited for the platform

23. Summary
Many additional portability issues
• replacing the backend is not enough!
AOP elegantly addresses them
• four classes of portability aspects
• encapsulate platform concerns in
separate libraries