Export EncodeBytesLen() in the encoder

[xichen2020]

Is it possible to export EncodeBytesLen() in the encoder APIs? My use case is that I need to encode a large number of items, each of which contains an ID, which in turn contains a prefix, a body, and a suffix, all of which are byte slices, e.g.,

type ID struct {
  Prefix []byte
  Body []byte
  Suffix []byte
}

What I'd like to achieve is to encode the ID object as if it were a single []byte so that I can avoid unnecessary byte copies during decoding. With the existing API, I'd have to concatenate the prefix/body/suffix and create a new byte slice to use the EncodeBytes method. However if we export EncodeBytesLen(), I can call EncodeBytesLen() to encode the number of bytes first, then write the raw bytes.

If that sounds reasonable, I'd be happy to put up a PR.

[vmihailenco]

Bytes is a slice (array) so you use EncodeArrayLen.

[vmihailenco]

Hm, no - I am wrong. Please send a PR.

[xichen2020]

Here it is: #120