title: ctypes reference double pointer
body: <p>I have a C function that the doxygen looks like this:</p>
  
  <pre><code>long function( classA * obj1,
                 classB * obj2,
                 classC ** obj3,
                 long value,
                 const char * name1,
                 const char * name2,
                 classD ** obj4,
                 classD ** obj5,
                 classD ** obj6 
                 )    
  </code></pre>
  
  <p>I need to call it from python and get the 3 last arguments to pass to another dll. Currently I can call the DLL fine, but if I try to pass the last 3 arguments to the other function I get an error like this:</p>
  
  <pre><code>WindowsError: exception: access violation writing 0x0000000000000000
  </code></pre>
  
  <p>I am probably doing something wrong in the ctypes side of things and I would appreciate some light on how to use it...</p>
  
  <p>The second DLL looks like this:</p>
  
  <pre><code>int function2(ClassD *  obj4)   
  </code></pre>
  
  <p>And currently I "assemble" the last 3 arguments like this:</p>
  
  <pre><code>  temp=ctypes.c_long*1
    obj = temp(0)
  </code></pre>
  
  <p>Also, is there any way of going from ctypes to swig? Apparently I can do the other way around using the long function.</p>