Ref4 method

P Ref4([
  1. X? o
])

Allocates o into slot '4', or reuses the existing slot '4' allocation if o is null.

Intended as a short-lived scratch reference within a single C call. Use RefUpdate4 if the callee may write back into the pointer.

Implementation

P Ref4([X? o]) => _Ref(o, '4');