The implementation of io.WriteString appears to allocate a new byte slice and copy the string into it:
w.Write([]byte(s)) Many third party libraries avoid the allocation and copy with techniques like: var b []byte sh := (*reflect.StringHeader)(unsafe.Pointer(&s)) bh := (*reflect.SliceHeader)(unsafe.Pointer(&b)) bh.Data = sh.Data bh.Len = sh.Len bh.Cap = sh.Len w.Write(b) I've seen so many different packages do this that it almost seems like a preferred idiom. Yet, it doesn't seem to be guaranteed safe by the rules in the "unsafe" package documentation; rule 6 comes close to allowing it but doesn't quite get there. And the fact that the standard library doesn't use it, in an obviously applicable place, is telling. So, what's the deal here? Is it safe or not? Can I use it in my own code? Must I shun libraries that use it? (Must I read the source code of every library I use, to see whether it uses it?) -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/CAAnpqKHoA74DfM5765vUfrH4V6RpBxg1DTkfn3ScN6MhjQwRTQ%40mail.gmail.com.
