c++11 - Use of enable_shared_from_this with multiple inheritance -

bi using enable_shared_from_this in code, , not sure if usage correct. code:

class a: public std::enable_shared_from_this<a> { public:     void foo1()     {         auto ptr = shared_from_this();      } };  class b:public std::enable_shared_from_this<b> { public:     void foo2()     {         auto ptr = shared_from_this();      } };  class c:public std::enable_shared_from_this<c> { public:     void foo3()     {         auto ptr = shared_from_this();      } };  class d: public a, public b, public c { public:     void foo()     {         auto ptr = a::shared_from_this();      } }; 

are these usage of make_shared_from_this() correct, assuming being called through shared_ptr of d?

indeed doing wrong. if have simple inheritance, inherit enable_shared_from this in base class, , derived class free. (of course you'll need downcast result)

if have multiple inheritance (like seems), must use trick described here , here :

/* trick allow multiple inheritance of objects  * inheriting shared_from_this.  * cf. https://stackoverflow.com/a/12793989/587407  */  /* first common base class  * of course, 1 should virtually inherit it.  */ class multipleinheritableenablesharedfromthis: public std::enable_shared_from_this<multipleinheritableenablesharedfromthis> { public:   virtual ~multipleinheritableenablesharedfromthis()   {} };  template <class t> class inheritable_enable_shared_from_this : virtual public multipleinheritableenablesharedfromthis { public:   std::shared_ptr<t> shared_from_this() {     return std::dynamic_pointer_cast<t>(multipleinheritableenablesharedfromthis::shared_from_this());   }   /* utility method downcast.    * useful when child doesn't inherit directly enable_shared_from_this    * wants use feature.    */   template <class down>   std::shared_ptr<down> downcasted_shared_from_this() {     return std::dynamic_pointer_cast<down>(multipleinheritableenablesharedfromthis::shared_from_this());   } }; 

then code becomes :

class a: public inheritable_enable_shared_from_this<a> { public:     void foo1()     {         auto ptr = shared_from_this();      } };  class b: public inheritable_enable_shared_from_this<b> { public:     void foo2()     {         auto ptr = shared_from_this();      } };  class c: public inheritable_enable_shared_from_this<c> { public:     void foo3()     {         auto ptr = shared_from_this();      } };  class d: public a, public b, public c { public:     void foo()     {         auto ptr = a::downcasted_shared_from_this<d>();      } };