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      1 #ifdef __cplusplus
      2 
      3 /*
      4   SwigPtr_PyObject is used as a replacement of PyObject *, where
      5   the INCREF/DECREF are applied as needed.
      6 
      7   You can use SwigPtr_PyObject in a container, such as
      8   
      9      std::vector<SwigPtr_PyObject>;
     10 
     11   or as a member variable:
     12   
     13      struct A {
     14        SwigPtr_PyObject obj;
     15        A(PyObject *o) : _obj(o) {
     16        }
     17      };
     18 
     19    or as a input/output value 
     20 
     21      SwigPtr_PyObject func(SwigPtr_PyObject obj) {     
     22        SwigPtr_PyObject out = PyString_FromFormat("hello %s", PyObject_AsString(obj));
     23        Py_DECREF(out);
     24        return out;
     25      }
     26 
     27    just remember to pair the object creation with the proper DECREF,
     28    the same as with plain PyObject *ptr, since SwigPtr_PyObject always add
     29    one reference at construction.
     30 
     31    SwigPtr_PyObject is 'visible' at the wrapped side, so you can do:
     32 
     33 
     34       %template(pyvector) std::vector<swig::SwigPtr_PyObject>;
     35 
     36    and all the proper typemaps will be used.
     37    
     38 */
     39 
     40 namespace swig {
     41   %ignore SwigPtr_PyObject;
     42   struct SwigPtr_PyObject {};
     43   %apply PyObject * {SwigPtr_PyObject};
     44   %apply PyObject * const& {SwigPtr_PyObject const&};
     45 
     46   %typemap(typecheck,precedence=SWIG_TYPECHECK_SWIGOBJECT,noblock=1) SwigPtr_PyObject const& "$1 = ($input != 0);";
     47 
     48 
     49   /* For output */
     50   %typemap(out,noblock=1)  SwigPtr_PyObject {
     51     $result = (PyObject *)$1;
     52     Py_INCREF($result);
     53   }
     54   
     55   %typemap(out,noblock=1)  SwigPtr_PyObject const & {
     56     $result = (PyObject *)*$1;
     57     Py_INCREF($result);
     58   }
     59   
     60 }
     61 
     62 %{
     63 namespace swig {
     64   class SwigPtr_PyObject {
     65   protected:
     66     PyObject *_obj;
     67 
     68   public:
     69     SwigPtr_PyObject() :_obj(0)
     70     {
     71     }
     72 
     73     SwigPtr_PyObject(const SwigPtr_PyObject& item) : _obj(item._obj)
     74     {
     75       Py_XINCREF(_obj);      
     76     }
     77     
     78     SwigPtr_PyObject(PyObject *obj, bool initial_ref = true) :_obj(obj)
     79     {
     80       if (initial_ref) {
     81         Py_XINCREF(_obj);
     82       }
     83     }
     84     
     85     SwigPtr_PyObject & operator=(const SwigPtr_PyObject& item) 
     86     {
     87       Py_XINCREF(item._obj);
     88       Py_XDECREF(_obj);
     89       _obj = item._obj;
     90       return *this;      
     91     }
     92     
     93     ~SwigPtr_PyObject() 
     94     {
     95       Py_XDECREF(_obj);
     96     }
     97     
     98     operator PyObject *() const
     99     {
    100       return _obj;
    101     }
    102 
    103     PyObject *operator->() const
    104     {
    105       return _obj;
    106     }
    107   };
    108 }
    109 %}
    110 
    111 /*
    112   SwigVar_PyObject is used to manage 'in the scope' PyObject * variables,
    113   as in
    114 
    115   int func () {
    116     SwigVar_PyObject obj = PyString_FromString("hello");
    117   }
    118 
    119   ie, 'obj' is created and destructed in the same scope from
    120   a python object that carries at least one reference value.
    121   
    122   SwigVar_PyObject just take care of applying the proper Py_DECREF.
    123 
    124   Hence, this class is purely internal and not visible at the wrapped side.
    125  */
    126 namespace swig {
    127   %ignore SwigVar_PyObject;
    128   struct SwigVar_PyObject {};
    129   %apply PyObject * {SwigVar_PyObject};
    130   %apply PyObject * const& {SwigVar_PyObject const&};
    131 }
    132 
    133 %{
    134 namespace swig {
    135   struct SwigVar_PyObject : SwigPtr_PyObject {
    136     SwigVar_PyObject(PyObject* obj = 0) : SwigPtr_PyObject(obj, false) { }
    137     
    138     SwigVar_PyObject & operator = (PyObject* obj)
    139     {
    140       Py_XDECREF(_obj);
    141       _obj = obj;
    142       return *this;      
    143     }
    144   };
    145 }
    146 %}
    147 
    148 
    149 #endif
    150