"cannot accept the address" and "cannot call the pointer method to"

Question

This compiles and works:

diff := projected.Minus(c.Origin)
dir := diff.Normalize()

This does not give (gives errors in the header):

dir := projected.Minus(c.Origin).Normalize()

Can someone help me understand why? (Go training)

These methods are:

// Minus subtracts another vector from this one
func (a *Vector3) Minus(b Vector3) Vector3 {
    return Vector3{a.X - b.X, a.Y - b.Y, a.Z - b.Z}
}

// Normalize makes the vector of length 1
func (a *Vector3) Normalize() Vector3 {
    d := a.Length()
    return Vector3{a.X / d, a.Y / d, a.Z / d}
}

Answer 1

The method Vector3.Normalize()has a pointer receiver, so calling this method requires a pointer to the value Vector3( *Vector3). In the first example, you store the return value Vector3.Minus()in a variable that will be of type Vector3.

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(&diff).Normalize()

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func pv(v Vector3) *Vector3 {
    return &v
}

:

dir := pv(projected.Minus(c.Origin)).Normalize()

Vector3, :

func (v Vector3) pv() *Vector3 {
    return &v
}

:

dir := projected.Minus(c.Origin).pv().Normalize()

:

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