Writing Code That Writes Code
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The document discusses the concept of code generation, emphasizing techniques such as code munging and inline code expansion. It provides a series of best practices for using code generators, including starting with hand-coded solutions and maintaining documentation. The author encourages thoughtful integration of code generation tools into development workflows while considering their cultural impact.
Writing Code That Writes Code
- 1. WRITING CODE that WRITES CODE STEVE MARSHALL
- 2. But why?
- 4. Code munging
- 5. Inline code expansion Code munging
- 6. Mixed code generation Inline code expansion Code munging
- 7. Partial class generation Mixed code generation Inline code expansion Code munging
- 8. Tier generation Partial class generation Mixed code generation Inline code expansion Code munging
- 9. Full domain language Tier generation Partial class generation Mixed code generation Inline code expansion Code munging
- 10. Full domain language Tier generation Partial class generation Mixed code generation Inline code expansion Code munging
- 11. Source code Code munger Output file
- 12. Full domain language Tier generation Partial class generation Mixed code generation Inline code expansion Code munging
- 13. Source code Inline code expander Output source code Compiler
- 14. Full domain language Tier generation Partial class generation Mixed code generation Inline code expansion Code munging
- 15. Source code Mixed code generator Output source code Compiler
- 16. Full domain language Tier generation Partial class generation Mixed code generation Inline code expansion Code munging
- 17. Definition file Partial class Templates generator Output base Custom derived class code class code Compiler
- 18. Full domain language Tier generation Partial class generation Mixed code generation Inline code expansion Code munging
- 19. Definition file Templates Tier generator Output source code Compiler
- 20. Full domain language Tier generation Partial class generation Mixed code generation Inline code expansion Code munging
- 22. What should I use?
- 23. Let me tell you a story…
- 24. One for the team.
- 29. 5. Integrate the generator into your workflow.
- 31. 7. Play nice with others.
Editor's Notes
- #2: Gonna talk about codegen. Steve Marshall - Interested in everything - Want to be a pirate - Y! Ents Why codegen - Don’t like repetition - Don’t like repetition - Interesting problem of scale - Lack of resources => be creative
- #3: Quality, consistency, single point of knowledge, eases bulk refactoring, improves architectural consistency, increases abstraction, increases morale. Quality Lots of code => inconsistencies Templates => consistent quality Consistency - Consistent naming - API style - No surprises Single Point of Knowledge Schema describes system simply Architecture documented, not embedded in code Facilitates Bulk Refactoring Faulty assumptions in hand coding mean refactoring lots of code Generation makes refactoring minimal Also: generation can compress project timelines => more time to design/prototype, less need to refactor Architectural Consistency - Generator encourages working within architecture - “generator doesn’t do that” can indicate that the feature doesn’t fit the architecture - Consistent, structured approach, regardless of team members joining/leaving Abstraction - Application logic is language-independent. Can easily port templates to other languages (eg. for performance, also: WSDL describing inputs/outputs) - Can easily review/validate abstract designs - Aids development of non-implementation code (tests, documentation, etc) High Morale Less gruntwork to do by hand More focus on interesting problems Higher morale Also: higher quality, consistent code => confidence and pride
- #4: Type of codegen… - Munging - Code expansion - Mixed codegen - Partial class gen - Tier gen - FDL
- #5: Type of codegen… - Munging - Code expansion - Mixed codegen - Partial class gen - Tier gen - FDL
- #6: Type of codegen… - Munging - Code expansion - Mixed codegen - Partial class gen - Tier gen - FDL
- #7: Type of codegen… - Munging - Code expansion - Mixed codegen - Partial class gen - Tier gen - FDL
- #8: Type of codegen… - Munging - Code expansion - Mixed codegen - Partial class gen - Tier gen - FDL
- #9: Type of codegen… - Munging - Code expansion - Mixed codegen - Partial class gen - Tier gen - FDL
- #11: Parses source code Produces some non-source output See documentation, linting, … Also: build header files, web service layers
- #13: Parses source for special keywords Replaces with production code eg. Embedding SQL in source à la Pro*C/SQLJ
- #15: Like inline code expansion, but output can be used as input (replaces in-place) Looks for specially formatted comments, fills comment-wrapped area with new production source eg. Marshalling code
- #17: Reads abstract definition with enough info to build classes Applies def’n to templates to output base classes Used with subclasses for custom behaviour Can be a stepping stone to tier generation
- #19: Generator builds a complete tier of your app (eg ORM) eg. Model-driven generation takes definition file and applies to templates Like partial class, but without special cases (or are codified in templates) Partial class generation requires extra code, tier doesn’t (but may have it)