Instructions for newcomers

[OnikenX]

Hi, I'm playing with rust and libp2p but most of the time I see myself changing the code in examples to work in my personal project.

The examples work fine in the rust-libp2p project itself but when I try it in a different project with my Cargo.toml errors begin to arise.

For example, in the example gossip-chat it gives me a dependecy error:

error[E0432]: unresolved import `libp2p::gossipsub::IdentTopic`
  --> src/gossipsub-chat.rs:54:39
     |
54 |     GossipsubEvent, GossipsubMessage, IdentTopic as Topic, MessageAuthenticity, ValidationMode,
     |                                       ^^^^^^^^^^^^^^^^^^^ no `IdentTopic` in `gossipsub`

an some methods not publics errors:

error[E0599]: no method named `listen_on` found for struct `ExpandedSwarm<Gossipsub, gossipsub::rpc_proto::Rpc, gossipsub::handler::HandlerEvent, gossipsub::handler::GossipsubHandler>` in the current scope
   --> src/gossipsub-chat.rs:119:11
    |
119 |     swarm.listen_on("/ip4/0.0.0.0/tcp/0".parse().unwrap()).unwrap();
    |     ------^^^^^^^^^
    |     |     |
    |     |     this is an associated function, not a method
    |     help: use associated function syntax instead: `ExpandedSwarm::<Gossipsub, gossipsub::rpc_proto::Rpc, gossipsub::handler::HandlerEvent, gossipsub::handler::GossipsubHandler>::listen_on`
    |
    = note: found the following associated functions; to be used as methods, functions must have a `self` parameter
    = note: the candidate is defined in an impl for the type `ExpandedSwarm<TBehaviour, TInEvent, TOutEvent, THandler>`

error[E0599]: no method named `dial_addr` found for struct `ExpandedSwarm<Gossipsub, gossipsub::rpc_proto::Rpc, gossipsub::handler::HandlerEvent, gossipsub::handler::GossipsubHandler>` in the current scope
   --> src/gossipsub-chat.rs:124:40
    |
124 |             Ok(to_dial) => match swarm.dial_addr(to_dial) {
    |                                  ------^^^^^^^^^
    |                                  |     |
    |                                  |     this is an associated function, not a method
    |                                  help: use associated function syntax instead: `ExpandedSwarm::<Gossipsub, gossipsub::rpc_proto::Rpc, gossipsub::handler::HandlerEvent, gossipsub::handler::GossipsubHandler>::dial_addr`
    |
    = note: found the following associated functions; to be used as methods, functions must have a `self` parameter
    = note: the candidate is defined in an impl for the type `ExpandedSwarm<TBehaviour, TInEvent, TOutEvent, THandler>`

and a method not found method:

error[E0599]: no method named `behaviour_mut` found for struct `ExpandedSwarm<Gossipsub, gossipsub::rpc_proto::Rpc, gossipsub::handler::HandlerEvent, gossipsub::handler::GossipsubHandler>` in the current scope
   --> src/gossipsub-chat.rs:140:50
    |
140 |                 Poll::Ready(Some(line)) => swarm.behaviour_mut().publish(topic.clone(), line.as_bytes()),
    |                                                  ^^^^^^^^^^^^^ method not found in `ExpandedSwarm<Gossipsub, gossipsub::rpc_proto::Rpc, gossipsub::handler::HandlerEvent, gossipsub::handler::GossipsubHandler>`

while my Cargo has these dependencies:

[package]
name = "rust-learning"
version = "0.1.0"
authors = ["OnikenX <OnikenX@pm.me>"]
edition = "2018"

[[bin]]
name = "gossipsub-chat"
path = "src/gossipsub-chat.rs"

[dependencies]
async-std = { version = "1.9.0", features = ["attributes"] }
futures = "0.3.14"
libp2p = { version = "0.36.0", features = ["tcp-tokio", "mdns", "floodsub", "mplex", "noise", "gossipsub", "deflate", "dns-async-std", "floodsub", "identify", "kad", "gossipsub", "mdns", "mplex", "noise", "ping", "plaintext", "pnet", "relay", "request-response", "secp256k1", "tcp-async-io", "uds", "wasm-ext", "websocket", "yamux", ] }
tokio = { version = "*", features = ["io-util", "io-std", "stream", "macros", "rt", "rt-multi-thread", "fs", "time", "sync"] }
serde = { version = "1.0.125", features = ["derive"] }
serde_json = "1.0.64"
once_cell = "1.7.2"
log = "0.4.14"
pretty_env_logger = "0.4.0"
env_logger = "0.8.3"

I've been copying some dependencies from the main Cargo.toml in the rust-libp2p repo but this still gives me these errors that I don't know how to fix without changing the code, something that I don't have to do if I run the code in using the main project repo(rust-libp2p) with its configuration.

I'm also new in rust this can be my ignorance on rust and cargo and nothing to do with libp2p itself, if someone can give me advice I would appreciate it very much and probably anyone who ends up here, if this is a common problem please give us an example Cargo.toml in the examples/ directory it would be even more helpful.

Thank you in advance.

[OnikenX]

Looks like I was using the master branch of the examples in my project when I was using the v0.36 package 😅
that was the only problem, basically for someone with the same problem change the repo version to the tag that is the same for your dependency.

[mxinden]

Correct. This is especially prominent as master contains some breaking changes on Swarm. See #2035 (review) for details.