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How to use local unpublished crate in Rust by cargo

Cargo is configured to look for dependencies on crates.io by defalut. However I want to use a local crate. Fortunately, cargo supports to use libraries ont only on crates.io, but also ther registries, git repositories or subdirectories on our local file system.

create a lib

Firstly, create a new package:

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$ cargo new test_crate --lib

Here we pass --lib because we’re making a library. Then the cargo generates:

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.
├── Cargo.lock
├── Cargo.toml
└── src
    └── lib.rs

1 directory, 3 files

Let’s do something in lib.rs.

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pub fn public_function_in_test_crate() {
    println!("called `public_function_in_test_crate`");
}

pub mod cool {
    pub fn cool_function() {
        println!("called `cool::cool_function`");
    }
}

set Cargo.toml

Then we create a new binary program use cargo new test_extern_crate and add a dependency section to our executable’s Cargo.toml and sepcify the path:

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[dependencies]
test_crate = {path = "../test_crate"}

or

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[dependencies.test_crate]
path = "../test_crate"

Now we can use our local crate test_crate as folliwing:

main.rs:

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extern crate test_crate;

use test_crate::cool;

fn main() {
    test_crate::public_function_in_test_crate();
    test_crate::cool::cool_function();
    cool::cool_function();
}

more details in more detals in Cargo book .