Конверсия управляемых языков в неуправляемые
- 2. Managed language = C#, Java, D etc. GC (garbage collector), Unicode, … Unmanaged language Something that compiles to native code More control, less safety C/C++, VHDL, etc.
- 3. Performance Stop-the-world GC Low-level control (e.g., SIMD) Collections (containers), multithreading Defense against reverse-engineering C#, Java are easy to decompile Hardware support CUDA, Xeon Phi Portability (surprise!) Sudden desire to write everything in С++
- 4. Lex the source code Build AST Resolve symbols Traverse the tree, translating it to a different language Perfect translation is (of course) impossible
- 5. Translate syntax with fidelity Fill the gaps in what’s missing Replace equivalent constructs List<> vector<> Handle cases where 1-to-1 mapping is impossible
- 6. Integral types Use types from <cstdint> int int32_t, byte uint8_t, etc. float/double as-is Extended precision types (System.Decimal) Need external libs Slightly different init rules
- 7. Unicode Most LoB apps do not absolutely require Unicode (nice to have) Relatively safe option: string std::wstring char wchar_t Slightly more careless option: string/char A completely safe solution has to allow strings to be nullptr I.e., you either use char* or option<string> Expensive, tedious, just use myString.empty() Unicode in source (identifiers, literals, …) won’t work
- 8. class Person { string name; int age; } class Person { std::string name; int32_t age; public: Person(); };
- 9. Managed languages Give types default values Allow initialization right in the declaration In both cases, initialization happens in the (generated) ctor In C++, types don’t have default values. So we are forced to make a constructor ourselves
- 10. Property = field+getter+setter Can be read or write-only Can be automatic Name of field not specified explicitly Offers no benefit over a field in C++ Can have an inline initializer More ctor abuse Two options here GetXxx/SetXxx (safe, tedious) __declspec(property) (not C++ standard, but nicer) int age; public int Age { get { return age; } set { age = value; } } // automatic public int Age { get; set; }
- 11. __declspec(property(get = GetAge, put = PutAge)) int Age; int GetAge() const { return age; } void PutAge(int value) { … } // later Person p; p.Age = 123; // calls PutAge()
- 12. Used in many places, e.g.: Handling UI interactions Property change notifications C++ doesn’t have them Boost.Signals Tricky since event subscription is done with += And unsubscription with −=
- 13. template <typename T> class INotifyPropertyChanged { public: signal<void(const T*, string)> PropertyChanged; };
- 14. class Player : public INotifyPropertyChanged<Player> { int age; public: __declspec(property(get = GetAge, put = PutAge)) int Age; int GetAge() const { return age; } void PutAge(int value) { if (value == age) return; PropertyChanged(this, "Age"); // oops, a string! (macro?) age = value; }
- 15. “The big problem” GC non-GC translation Store everything as shared_ptr Replace every `new` with make_shared Detecting use-cases for make_unique very difficult Circular references (weak_ptr<>?)
- 16. References require#includes Need a list of typeheader for STL etc. Circular references may need forward declarations Header groupings (at namespace or folder level) Very tricky internal consistency (topological sort) Also a good idea for IDEs
- 17. Type translation is (relatively) easy int int32_t List<T> vector<T> Function call translation is harder List.Add() vector.emplace_back(), but… Value vs ref. stuff
- 18. We need two converters One for .H files Another for .CPP files (implementation) The option of doing everything inline isn’t considered There are situations where 100% inlining doesn’t work
- 20. Naming convention Clean Unicode handling Automated API mapping
- 21. Questions? dn@jetbrains.com @dnesteruk Come to the JB booth! (R#C++, CLion)