How do I use external crates in Rust?

Question

I'm trying to work with the rust-http library, and I'd like to use it as the basis for a small project.

I have no idea how to use something that I can't install via rustpkg install <remote_url>. In fact, I found out today that rustpkg is now deprecated.

If I git clone the library and run the appropriate make commands to get it built, how do I use it elsewhere? I.e. how do I actually use extern crate http?

Answer 1

Since Rust 1.0, 99% of all users will use Cargo to manage the dependencies of a project. The TL;DR of the documentation is:

1. Create a project using cargo new

2. Edit the generated Cargo.toml file to add dependencies:

   [dependencies] old-http = "0.1.0-pre" 

3. Access the crate in your code:

   Rust 2021 and 2018

   use old_http::SomeType; 

   Rust 2015

   extern crate old_http; use old_http::SomeType; 

4. Build the project with cargo build

Cargo will take care of managing the versions, building the dependencies when needed, and passing the correct arguments to the compiler to link together all of the dependencies.

Read The Rust Programming Language for further details on getting started with Cargo. Specifying Dependencies in the Cargo book has details about what kinds of dependencies you can add.

Answer 2

Update

For modern Rust, see this answer.

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Original answer

You need to pass the -L flag to rustc to add the directory which contains the compiled http library to the search path. Something like rustc -L path-to-cloned-rust-http-repo/build your-source-file.rs should do.

Tutorial reference