property-cpp.md

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property (C++) | Microsoft Docs		11/04/2016			cpp-language		language-reference	property_cpp	C++	property __declspec keyword __declspec keyword [C++], property	f3b850ba-bf48-4df7-a1d6-8259d97309ce	7	mikeblome	mblome	ghogen

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.

Syntax

  
      __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  

Remarks

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

Example

// 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;  
}  

See Also

__declspec
Keywords