Delphi2Cpp Tools and Best Practices for Seamless Migration
Overview
Delphi2Cpp is a toolchain and methodology for porting Delphi (Object Pascal) codebases to modern C++. The goal is a maintainable, idiomatic C++ result rather than literal line-for-line translation.
Key Tools
| Tool | Purpose |
|---|---|
| Delphi2Cpp core converter | Transforms Pascal/Delphi syntax and constructs into C++ equivalents (classes, methods, basic types). |
| AST analysis utilities | Parse Delphi code to build an abstract syntax tree for precise refactoring and pattern detection. |
| RTTI/Type-mapping library | Maps Delphi runtime type information and common RTL/VCL types to C++ types or wrapper classes. |
| Compatibility wrappers | Provide C++ wrappers for Delphi-specific libraries (String/Unicode helpers, dynamic arrays, TObject lifecycle). |
| Build integration scripts | Automate project file generation (CMake, MSBuild) and dependency management. |
| Unit-test/CI adapters | Convert or rewire Delphi unit tests to C++ testing frameworks and integrate into CI pipelines. |
Best Practices
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Inventory and prioritize
- Scan: Use static analysis to catalog units, third-party libs, and platform-specific code.
- Prioritize: Migrate core/shared libraries first, UI or platform code later.
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Adopt an incremental strategy
- Migrate modules one at a time, keep both builds working via adapters/wrappers, and run regression tests after each module.
-
Preserve semantics, then optimize
- First aim for semantic parity. After tests pass, refactor translated code into idiomatic C++ (RAII, smart pointers, STL).
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Define consistent type mappings
- Establish mappings for strings (Unicode handling), dynamic arrays, sets, records/structs, and pointers to ensure uniform behavior.
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Wrap Delphi runtime and VCL selectively
- Implement thin compatibility layers where full rewrite is impractical; replace incrementally with native C++ UI frameworks where feasible.
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Automate conversions and enforce style
- Use conversion scripts for repetitive patterns and run linters/formatters (clang-format, clang-tidy) to maintain code quality.
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Retain and convert tests
- Port unit tests early; use test adapters or translate tests to a C++ framework (GoogleTest, Catch2) to validate behavior.
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Handle memory and object lifetime explicitly
- Replace Delphi’s memory management idioms with RAII and smart pointers (unique_ptr, shared_ptr) to avoid leaks and undefined behavior.
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Manage platform and compiler differences
- Abstract OS-specific code, test on target compilers (MSVC, Clang, GCC), and use CMake to manage cross-platform builds.
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Document decisions and create migration guidelines
- Keep a living migration guide covering type mappings, common pitfalls, and examples for future maintainers.
Common Pitfalls & Remedies
- String/encoding mismatches: Standardize on UTF-8 in C++ and provide conversion utilities.
- Event/callback patterns: Translate Delphi method pointers to std::function or functors, keeping lifecycle in mind.
- Runtime assumptions (global state, Init sections): Recreate necessary initialization in controlled C++ constructors or module init routines.
- Extensive use of RTTI: Implement reflection-like helpers or redesign code to avoid heavy RTTI reliance.
Suggested Migration Workflow (4 phases)
- Assessment & planning (inventory, tests, prioritization).
- Core library migration (types, utils, data models).
- Peripheral systems (UI, platform-specific code) with wrappers where needed.
- Cleanup & optimization (idiomatic C++, performance tuning, remove compatibility layers).
Quick Example Patterns
- Delphi dynamic array -> std::vector
- Delphi string (UnicodeString) -> std::u16string or std::string (UTF-8) with converters
- TObject ownership -> std::unique_ptr / std::shared_ptr
- Method pointers/events -> std::function or observer pattern
Date: February 5, 2026
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