Slices

Canonical guidance

• remember slices share backing arrays until a copy or reallocation breaks sharing
• use copy when ownership should be distinct
• reason about length and capacity when appending

Use when

• ordered collections
• buffers
• batched processing

Avoid

• returning subslices that accidentally retain large backing arrays
• mutating shared slices without clear ownership
• assuming append always mutates in place

Preferred pattern

func Clone(in []byte) []byte {
	out := make([]byte, len(in))
	copy(out, in)
	return out
}

Anti-pattern

• keeping a tiny subslice of a huge buffer alive for a long time

Explanation: This anti-pattern is tempting because subslices are cheap, but they can retain far more memory than intended.

Why

• slice semantics are simple once ownership and aliasing stay explicit