Managing Pointers in Vector3 Method Calls

While attempting to chain method calls on the Vector3 struct, you may encounter errors related to taking the address of values and calling pointer methods. This article examines these errors and guides you on how to address them.

Understanding Pointer and Value Receivers

Methods in Go can have either pointer or value receivers. A pointer receiver allows the method to modify the original struct, while a value receiver creates a copy of the struct locally within the method.

Origin of the Errors

In your example, Vector3.Normalize() has a pointer receiver, meaning you need a pointer to a Vector3 variable to call it. When calling dir := projected.Minus(c.Origin).Normalize(), you're trying to take the address of the return value of projected.Minus(c.Origin), which is a value. This is not allowed in Go, hence the error.

Workarounds

To resolve this, you have several options:

• Assign to a Variable: Assign the return value of projected.Minus(c.Origin) to a variable and then call Normalize() on that variable.
• Modify Method Receivers: Change Vector3 methods to have value receivers, eliminating the need to take addresses. However, this may not be feasible if the methods require modifying the struct.
• Return Pointers: Modify Vector3 method return types to return pointers. This eliminates the need for taking addresses as the returned pointer can directly serve as the receiver for pointer-based methods.
• Create a Helper Function: Create a helper function that returns a pointer to the Vector3 value.

Consistency is Key

It's essential to maintain consistency in receiver and result types within a struct. If most methods in Vector3 have pointer receivers, keep all receivers as pointers. Similarly, maintain consistency in return types.

Performance Considerations

With Vector3 consisting only of float64 values, performance differences between pointer and value receivers may be negligible. However, strive for consistency and avoid mixing receiver types within the struct.