Use `impl From` instead of `trait ToMultiaddr`

[crackcomm]

It seems to me that there is too much of to_* and from_* when it should be enough to use .into() and single impl From.

[dignifiedquire]

Yes makes more sense probably. Though I am not sure, is there any case were you shouldn't use impl From or is it okay to use for all conversions?

[crackcomm]

Usage of impl From should be limited to use cases that are conversions between types.

Traits like ToString or FromStr should be implemented in cases of deserialization/serialization when input can be invalid but output is always possible.

In this case it seems perfectly fine and more valid to have:

impl From<Ipv4Addr> for Multiaddr

instead of

impl ToMultiaddr for Ipv4Addr

because as such it is only a type conversion.

[dignifiedquire]

Thanks for the explanation.

[tomaka]

Note that this should be TryFrom and not just From, because the conversion can return an error.

[jcc333]

So I'd love to contribute to this project with the caveat that I'm coming from a c++/scala/haskell background and trying to learn rust so there might be a vocabulary gap. That said I have a couple of questions around the context of this issue:

• Is there a better issue at which I can direct my efforts?
• Is this still an issue to use From, or is it TryFrom and now the library requires a nightly compiler?
• Is this issue resolved better by a TryFrom for each protocol to ensure a homogeneous interface, by TryFrom instances for the types which might fail and From instances for those types which are assured of success, or by waiting until TryFrom becomes stable?
• (rust question) Should the From/TryFrom instances target, for example, impl<'a> From<&'a SocketAddr> for Multiaddr or impl From<SocketAddr> for MultiAddr?

[mxinden]

Closing here since this is addressed with https://github.com/multiformats/rust-multiaddr/pull/40.

@jcc333 let us know in case you would still like to contribute.