Why I can't init static members - c++

Question

I have a class MotionDirection with static members. The source code of the class is below. But I just can not initialize the static members of the class and I can get the reason. So the problem is in the MotionDirection.cpp, see the comments for the details about the compiler errors.
MotionDirection.h
#ifndef MOTION_DIRECTION
#define MOTION_DIRECTION
namespace game{
class IntPosition;
class MotionDirection {
private:
IntPosition* positionDisplacement;
float angle;
MotionDirection* returnDirection;
public:
MotionDirection( IntPosition* positionDisplacement, float angle );
void setReturnDirection ( MotionDirection* returnDirection );
IntPosition* getPositionDisplacement();
float getAngle();
MotionDirection* getReturnDirection();
static MotionDirection* NONE;
static MotionDirection* LEFT;
static MotionDirection* RIGHT;
static MotionDirection* UP;
static MotionDirection* DOWN;
static void initStatics();
};
}
#endif
MotionDirection.cpp
#include "MotionDirection.h"
#include "IntPosition.h"
namespace game{
MotionDirection::NONE = new MotionDirection ( new IntPosition( 0, 0), 0.0f );
// here I get an error:
// MotionDirection.cpp:10:5: error: 'NONE' in 'class game::MotionDirection' does not name a type
MotionDirection::MotionDirection( IntPosition* positionDisplacement, float angle ) {
this->positionDisplacement = positionDisplacement;
this->angle = angle;
}
void MotionDirection::setReturnDirection ( MotionDirection* returnDirection ) {
this->returnDirection = returnDirection;
}
IntPosition* MotionDirection::getPositionDisplacement() {
return positionDisplacement;
}
float MotionDirection::getAngle() {
return angle;
}
MotionDirection* MotionDirection::getReturnDirection() {
return returnDirection;
}
void MotionDirection::initStatics () {
MotionDirection::NONE = new MotionDirection ( new IntPosition( 0, 0), 0.0f );
MotionDirection::LEFT = new MotionDirection ( new IntPosition(-1, 0), 180.0f );
MotionDirection::RIGHT = new MotionDirection ( new IntPosition( 1, 0), 0.0f );
MotionDirection::UP = new MotionDirection ( new IntPosition( 0,-1), 90.0f );
MotionDirection::DOWN = new MotionDirection ( new IntPosition( 0, 1), 270.0f );
}
MotionDirection::initStatics();
// or here I get an error:
// MotionDirection.cpp:45:35: error: expected constructor, destructor, or type conversion before ';' token
}
P.S. This is Android-NDK project, I run compilation from the cygwin console.

Answer 1

First error
Just replace
MotionDirection::NONE = new MotionDirection ( new IntPosition( 0, 0), 0.0f );
with
MotionDirection* MotionDirection::NONE = new MotionDirection ( new IntPosition( 0, 0), 0.0f );
Note MotionDirection* type before name of the variable: you need to provide compiler with a type.
Second error
You can't put expressions out of function blocks. There are two ways to do this "right":
1.
Make initStatics() return value.
Add private static variable.
Initialize new static variable by assigning value of initStatics() to it.
2.
Add nested class.
Write call to initStatics() in its constructor.
Add private static variable of that nested class.