Migrating Legacy Code to Delphi
Modernizing legacy code is challenging but rewarding. Here's a practical approach.
Assessment
Before migrating, assess your current situation:
- Code Inventory: What do you have?
- Dependencies: What do you rely on?
- Risk Areas: What's most fragile?
- Test Coverage: What's tested?
Migration Strategy
Approach 1: Big Bang
Migrate everything at once. Best for small projects.
Pros: Quick, clean break
Cons: High risk, requires coordination
Approach 2: Incremental
Migrate piece by piece. Recommended for larger projects.
Pros: Lower risk, easier to manage
Cons: Longer timeline, temporary complexity
Approach 3: Strangler Pattern
Build new functionality in Delphi while gradually replacing old code.
Step-by-Step Guide
Phase 1: Preparation
1. Create comprehensive tests for existing functionality
2. Document current behavior
3. Set up Delphi environment
4. Create migration plan
Phase 2: Migration
1. Start with low-risk components
2. Migrate and test each piece
3. Update integrations
4. Validate functionality
Phase 3: Validation
1. Run all tests
2. Performance comparison
3. User acceptance testing
4. Monitoring in production
Common Pitfalls
- Underestimating complexity
- Skipping tests
- Rushing the process
- Ignoring documentation
Success Metrics
Track your progress:
- Code coverage
- Build times
- Bug rates
- Team velocity
Good luck with your migration!