Create your own lib

How to implement extra feature to `lib`.

lib hi.rs

#![allow(unused)]
fn main() {
// 👇 exclamation ! mean apply to whole file.
#![cfg(feature = "hi")]
pub fn hi(){
  println!(":#?", base64::encode("hi"));
}
}

lib Cargo.toml

[package]
name = "foo"

[dependencies]
# optional true = include only when need 👇
base64 =  { version = "0.13", optional = true }

[features]
hi = ["dep:base64"] # 👈 related crate.

How to use extra feature from `lib`.

app Cargo.toml

[package]
name = "bar"

[dependencies]
# To include feature named "hi" 👇
foo = { version = "1", features = ["hi"] }

How to use your `lib` from `path`

[dependencies]
pyth-sdk-solana = { path = "../pyth-sdk-solana" }

How to use your `lib` from `github`

[dependencies]
pyth-sdk-solana = { git = "https://github.com/pyth-network/pyth-sdk-rs", rev = "75e2742" }

What common traits we should derive?

Debug
Send for Mutex
Sync for Arc
Clone
Default
PartialEq, PartialOrd, Hash, Eq, and Ord for comparison.
Serialize, Deserialize

💡 You can read more about this at at Rust for Rustaceans

Which function restrictions shall we use?

#![allow(unused)]
fn main() {
// Take owned String, return owned String.
fn hello(foo: String) -> String

// Take ref to str, return Copy on Write.
fn hello(foo: &str) -> Cow<'_, str>

// Take impl, return impl.
fn hello(foo: impl AsRef<str>) -> impl AsRef<str>
}

💡 You can read more about Cow here 👉 6 things you can do with the Cow 🐄 in Rust 🦀