Middleware Chains - Nil pointer dereference

[inzanez]

Hi

I was playing around building different middleware chains on the fly. I was using a slice:
middleware vestigo.Middleware[]
for that purpose. This sometimes resulted in a crash with nil pointer dereference / invalid memory access. I traced it back to a function in 'router.go' in the vestigo package:

func buildChain(f http.HandlerFunc, m ...Middleware) http.HandlerFunc {
    // if our chain is done, use the original handlerfunc
    if len(m) == 0 {
        return f
    }
    // otherwise nest the handlerfuncs
    return m[0](buildChain(f, m[1:cap(m)]...))
}

I replaced the line
return m[0](buildChain(f, m[1:cap(m)]...))
with
return m[0](buildChain(f, m[1:len(m)]...))

on my local sources, now everything is fine. I was wondering why you were using cap here at any rate? Wouldn't using 'len' be safer?