Content modification during io::copy

[alishir]

Hi all,
Sorry for the beginner's question, I want to modify the content of a byte stream during io::copy, for example replacing all A characters with B. Should I implement custom Future such as Copy?

[Darksonn]

You do not necessarily need to implement it with a custom Future like io::copy does, but it is certainly an option. Some other options are:

1. An io::copy like utility could also be written with async/await syntax using a loop or tokio::select!.
2. You can implement an AsyncRead wrapper that performs the conversion and use it with the ordinary io::copy.