Talk:C++Builder Keyword Extensions

__delphirtti

Hello,

Can we add "__delphirtti(...)" to the list of keyword extensions?

It's similar to __classid except that it returns the TypeInfo* of the type [not the metaclass]. Earlier versions of C++Builder allowed __delphirtti(..) for Interface and DynamicArray<..> types. Now we allow __delphirtti(...) for any publishable types [i.e. types that can appear in the __published section of a class].

The following example illustrates simple usage of __delphirtti:

  static bool validateTypeInfo(PTypeInfo pInfo, TTypeKind kind, const char* name)
  {
    VERIFY(pInfo != 0);    
    
    if ((pInfo->Kind != kind) || (AnsiString(pInfo->Name) != name))
      printf("ERROR: Kind(%d), Name(%s)\n", pInfo->Kind, AnsiString(pInfo->Name).c_str());
      
    VERIFY(pInfo->Kind == kind);    
    VERIFY(strcmp(AnsiString(pInfo->Name).c_str(), name) == 0);
    return true;
  }
  
  bool test()
  {
    validateTypeInfo(__delphirtti(ITest), tkInterface, "ITest");
    validateTypeInfo(__delphirtti(DynamicArray<double>), tkDynArray, "TDoubleDynArray");
    validateTypeInfo(__delphirtti(TSampleStruct), tkClass, "TSampleStruct");
    validateTypeInfo(__delphirtti(int), tkInteger, "int");
    validateTypeInfo(__delphirtti(AnsiString), tkLString, "AnsiString");
    validateTypeInfo(__delphirtti(WideString), tkWString, "WideString");
    validateTypeInfo(__delphirtti(UnicodeString), tkUString, "UnicodeString");
    validateTypeInfo(__delphirtti(Variant), tkVariant, "Variant");
    validateTypeInfo(__delphirtti(Set<SampleEnum, etNone, etALot>), tkSet, "Set");
    validateTypeInfo(__delphirtti(OleVariant), tkVariant, "OleVariant");
    validateTypeInfo(__delphirtti(Currency), tkFloat, "Currency");
    validateTypeInfo(__delphirtti(TDateTime), tkFloat, "TDateTime");
    return true;
  }

There are two things to keep in mind with __delphirtti:

1. 1. C++ does not have strong aliases. So __dephirtti(xxx) of typedefs will always return the 'Name' of the first typedef the compiler encountered. You can see that with DynamicArray types.

1. 2 Previously C++ code that wanted the typeinfo of a Delphi class would use "__classid(className)->ClassInfo();". This is less efficient as the TypeInfo is retrieve from the meta class at runtime. You can now just use "__delphirtti(className);".

__declspec

Maybe we should have a single entry for __declspec (not to list all the attributes).

Vadimb 06:23, 1 July 2011 (PDT)