title: Objective C LValue required as unary '&' operand
body: <p>In my code, I get this error when I <em>try</em> to get a pointer to my class property.<br>
  (I wrote a small *.OBJ file translator in Python, discarding the normals)<br>
  CODE:  </p>
  
  <pre><code>
  //line: line of text
  const char *str = [line UTF8String];  
  Point3D *p1, *p2, *p3;
  p1 = [Point3D makeX:0 Y:0 Z:0];
  p2 = [Point3D makeX:0 Y:0 Z:0];
  p3 = [Point3D makeX:0 Y:0 Z:0];
  sscanf(str, "t %f,%f,%f %f,%f,%f %f,%f,%f",(&[p1 x]),&([p1 y]),&([p1 z]),&([p2 x]),&([p2 y]),&([p2 z]),&([p3 x]),&([p3 y]),&([p3 z]));
  Triangle3D *tri = [Triangle3D make:p1 p2:p2 p3:p3];
  </code></pre>