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property (C++)

Microsoft Specific

This attribute can be applied to non-static "virtual data members" in a class or structure definition. The compiler treats these "virtual data members" as data members by changing their references into function calls.

__declspec( property( get=get_func_name ) ) declarator 
__declspec( property( put=put_func_name ) ) declarator 
__declspec( property( get=get_func_name, put=put_func_name ) ) declarator

When the compiler sees a data member declared with this attribute on the right of a member-selection operator ("." or "->"), it converts the operation to a get or put function, depending on whether such an expression is an l-value or an r-value. In more complicated contexts, such as "+=", a rewrite is performed by doing both get and put.

This attribute can also be used in the declaration of an empty array in a class or structure definition. For example:

__declspec(property(get=GetX, put=PutX)) int x[];

The above statement indicates that x[] can be used with one or more array indices. In this case, i=p->x[a][b] will be turned into i=p->GetX(a, b), and p->x[a][b] = i will be turned into p->PutX(a, b, i);

END Microsoft Specific

// declspec_property.cpp
struct S {
   int i;
   void putprop(int j) { 
      i = j;
   }

   int getprop() {
      return i;
   }

   __declspec(property(get = getprop, put = putprop)) int the_prop;
};

int main() {
   S s;
   s.the_prop = 5;
   return s.the_prop;
}

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