ICS 121: Code Generation and Reverse Engineering

Code generation is the process of using a tool that outputs program source code based on some specification
Popular types of code generation (characterized by the type of input specification)
- Wizards: built into IDEs, prompt the user for choices, then generates code and templates for the developer to fill in.
- UML tools: Reads a UML design, generates many class files with templates for operations. Some can generate implementations of state charts.
- Specification based: reads a custom file format and generates code to implement that specification. E.g., torque reads an XML specification of a database and outputs an SQL schema and Java code to access that database.
- Record-and-playback: often used in testing, records keyboard mouse events and generates script to repeat that test later
- Source-to-source: Reads a specification that is embedded in source code (as javadoc tags) to generate related source code. E.g, XDoclet and JUnitDoclet

Usually it is better to build and use (better) libraries than to generate large amounts of code
Code generation is useful when:
- You are building a static GUI with standard widgets, e.g., a dialog box
- You must implement a large application program skeleton, e.g., MFC
- One body of code is just a "mirror" of other code, e.g., code to load and save objects from the database
- UML or JUnitDoclet templates help automate the first steps of new code development
- Very similar code must be generated for multiple platforms, e.g., slightly different versions of an SQL schema for use with different vendor's databases
Often code generation is mainly done at one point in the development process and then custom coding is done
Often the generated code is hard to understand and maintain

Reverse engineering is the process of reading code and producing design documents.
Examples:
- Use a GUI builder to edit a dialog box, then later open that same file in the same GUI builder again.
- Use a UML tool to reverse engineer a UML design from source code: ArgoUML demo
"Round-trip engineering" means that one tool can generate code, and reverse engineer the same code that it generated. This can sometimes work even if you edit the code with a text editor.

You are trying to understand code that was given to you
You want to see how much your implementation has diverged from your original design
You are continuing to use a round-trip engineering tool like Together Control Center