Question

take a look at the following code :

if( down == null || down.GetFace() != Face.None || down.GetFace() != Face.Partial )
{  
    // I called GetFace() two times
    // How can i avoid to call it two times, and still putting inside that if
}  

Thank you!

Answer 1

Refactor to a method:

private bool IsFaceNoneOrPartial(Down down)
{
   var face = down.GetFace();

   return face != Face.None || face != Face.Partial;
}

// Your code is now:
if( down == null || IsFaceNoneOrPartial(down))
{

}