Can we use Go generics to refine some of the utilities for reading C types

[brianmcgee]

We have a few methods for reading arrays from C. They are all identical except for the return type.

Can we use generics to combine them?

nixos-facter/pkg/hwinfo/utils.go

Lines 10 to 56 in 7f1b1c4

	func ReadStringList(list *C.str_list_t) (result []string) {
	for entry := list; entry != nil; entry = entry.next {
	result = append(result, C.GoString(entry.str))
	}
	return result
	}
	func ReadUint64Array(arr unsafe.Pointer, length int) []uint64 {
	start := uintptr(arr)
	result := make([]uint64, length)
	for i := range result {
	next := start + uintptr(i*C.sizeof_uint64_t)
	result[i] = *((*uint64)(unsafe.Pointer(next)))
	}
	return result
	}
	func ReadUintArray(arr unsafe.Pointer, length int) []uint {
	start := uintptr(arr)
	result := make([]uint, length)
	for i := range result {
	next := start + uintptr(i*C.sizeof_uint)
	result[i] = *((*uint)(unsafe.Pointer(next)))
	}
	return result
	}
	func ReadIntArray(arr unsafe.Pointer, length int) []int {
	// TODO see if we can use generics to combine some of these methods
	start := uintptr(arr)
	result := make([]int, length)
	for i := range result {
	next := start + uintptr(i*C.sizeof_uint)
	result[i] = *((*int)(unsafe.Pointer(next)))
	}
	return result
	}
	func ReadByteArray(arr unsafe.Pointer, length int) []byte {
	start := uintptr(arr)
	result := make([]byte, length)
	for i := range result {
	next := start + uintptr(i*C.sizeof_uint)
	result[i] = *((*byte)(unsafe.Pointer(next)))
	}
	return result
	}

[brianmcgee]

@Mic92 recommends looking for unsafe slice, you can give it a pointer and a length.

[Mic92]

For strings you need to keep your function for the rest you could make a generic method with a type flag T that creates an unsafe slice and than copy the contents to a slice of type T