C ++ and reflection on the knee

It took recently to be able to access the field in the structure by its name - write, read the value. And so that the performance of those places where it is not used has not changed.
Here's what happened:

Copy Source | Copy HTML TUser user; user.StoreValue(); double SalaryRef; user.SetField( "Salary" , SalaryRef); // user.GetField( "Salary" , SalaryRef); // - // , - double Salary = user.GetField< double >( "Salary" );

1. Copy Source | Copy HTML TUser user; user.StoreValue(); double SalaryRef; user.SetField( "Salary" , SalaryRef); // user.GetField( "Salary" , SalaryRef); // - // , - double Salary = user.GetField< double >( "Salary" );
2. Copy Source | Copy HTML TUser user; user.StoreValue(); double SalaryRef; user.SetField( "Salary" , SalaryRef); // user.GetField( "Salary" , SalaryRef); // - // , - double Salary = user.GetField< double >( "Salary" );
3. Copy Source | Copy HTML TUser user; user.StoreValue(); double SalaryRef; user.SetField( "Salary" , SalaryRef); // user.GetField( "Salary" , SalaryRef); // - // , - double Salary = user.GetField< double >( "Salary" );
4. Copy Source | Copy HTML TUser user; user.StoreValue(); double SalaryRef; user.SetField( "Salary" , SalaryRef); // user.GetField( "Salary" , SalaryRef); // - // , - double Salary = user.GetField< double >( "Salary" );
5. Copy Source | Copy HTML TUser user; user.StoreValue(); double SalaryRef; user.SetField( "Salary" , SalaryRef); // user.GetField( "Salary" , SalaryRef); // - // , - double Salary = user.GetField< double >( "Salary" );
7. Copy Source | Copy HTML TUser user; user.StoreValue(); double SalaryRef; user.SetField( "Salary" , SalaryRef); // user.GetField( "Salary" , SalaryRef); // - // , - double Salary = user.GetField< double >( "Salary" );
8. Copy Source | Copy HTML TUser user; user.StoreValue(); double SalaryRef; user.SetField( "Salary" , SalaryRef); // user.GetField( "Salary" , SalaryRef); // - // , - double Salary = user.GetField< double >( "Salary" );

The whole secret in the "magic bubbles" - in the class from which TUser is inherited, and one function - StoreValue ().
Details under the cut.

Important: This solution is cross-platform, it requires only STL and the C ++ compiler, which “can” templates.
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At the beginning - the synonyms of types - in order to make it easier to change in the case of experiments.

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1. typedef std :: string TWString;
2. typedef __int64 bigint;
4. const double DBL_NULL = 0 ;
5. const bigint INT_NULL = - 1 ;
6. const TWString STR_NULL = TWString ();

The base class, which provides "goodies"

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1. struct BaseType
2. {
3. bool isstored;
4. enum BaseValueState {bvsStore, bvsSet, bvsGet, bvsErase};
5. BaseType (): IsStored ( false )
6. {
7. }
8. virtual ~ BaseType ()
9. {
10. if (IsStored)
11. {
12. int tempInt = int ();
13. double tempDbl = double ();
14. TWString tempStr = TWString ();
15. FieldStorage ( "" , tempInt, bvsErase);
16. FieldStorage ( "" , tempStr, bvsErase);
17. FieldStorage ( "" , tempDbl, bvsErase);
18. }
19. }
20. virtual void StoreValue () = 0 ;
22. template < class T >
23. void FieldStorage ( const TWString & Tag, T & Value,
24. BaseValueState State = bvsStore)
25. {
26. typedef std :: map < void *, std :: map < TWString , T *>> FieldMap;
27. static FieldMap Values;
28. static T Empty = T ();
29. if (! IsStored)
30. IsStored = true ;
31. switch (State)
32. {
33. case bvsStore:
34. Values ​​[ this ] [Tag] = & Value;
35. break ;
36. case bvsSet:
37. {
38. T * Ptr = Values ​​[ this ] [Tag];
39. if (Ptr)
40. * Ptr = Value;
41. }
42. break ;
43. case bvsGet:
44. {
45. T * Ptr = Values ​​[ this ] [Tag];
46. Value = (Ptr)? * Ptr: Empty;
47. }
48. break ;
49. case bvsErase:
50. Values.erase ( this );
51. break ;
52. }
53. }
55. template <typename T >
56. void GetField ( const TWString & Tag, T & Value)
57. {
58. FieldStorage (Tag, Value, bvsGet);
59. }
61. template <typename T >
62. void SetField ( const TWString & Tag, T & Value)
63. {
64. FieldStorage (Tag, Value, bvsSet);
65. }
67. template <typename T >
68. T GetField ( const TWString & Tag)
69. {
70. T Value;
71. FieldStorage (Tag, Value, bvsGet);
72. return Value;
73. }
74. };

And here we are inherited from it:

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1. struct TUser : public BaseType
2. {
3. TUser ( int AId = INT_NULL, const TWString & ALogin = STR_NULL, const double ASalary = DBL_NULL)
4. : Id (AId), Login (ALogin), Salary (ASalary)
5. {}
6. bigint Id;
7. TWString Login;
8. double Salary;
9. void StoreValue ()
10. {
11. FieldStorage ( "Id" , Id);
12. FieldStorage ( "Login" , Login);
13. FieldStorage ( "Salary" , Salary);
14. }
15. };